When Mohammed Tariq was seven years old he left Mirpur in Pakistan and arrived in Bradford. It was 1965, and his clearest memory is the cold. ‘Oh, it was bleak, Yorkshire was very bleak. You would get snow in the winter and rain in the summer.’ His father spoke a little English, his mother none. They were one of the first Pakistani families to settle in Bradford, and they started a business - a butcher’s and grocery shop.

In 1974 his parents sold up and flew home to Kashmir. Their sons stayed behind. Tariq moved to east London, and studied business; then to Paisley, to work in his uncle’s restaurant. The Scottish were friendly, he thought, but the hours were long, and when his uncle returned to Pakistan in 1984, Tariq moved back south to London, into the business he had known from childhood. His brother had opened one of Southall’s first halal butcher’s shops, and Tariq became the manager, working there with two more brothers besides. Before long it was one of the busiest shops in west London.

By 1993 there were 20 other halal butchers in Southall. The shop was taking over £40,000 a week, and Tariq wanted to expand - perhaps even start a franchise - but his brother disagreed. The pair fell out. For eight months Tariq drove a mini cab, but he had a wife, two young sons and ambition, and was frustrated - until he spotted an empty shop at the end of the high street, with a big car park round the back. On 19 March 1994, a new green sign went up above the door: Tariq Halal Meat.

‘The first three months, it was very difficult. I had just two butchers and myself, and we sold only meat. I would have my binoculars out on the pavement, looking to see where the next customer would come from. To the Asian mentality this wasn’t the right location; they want to be seen right among the crowd, and this part of Southall was dead. Nobody gave us hope. But I was looking at the car park, thinking, two or three years down the line...’

Tariq worked hard. For a time he slept in a bed above the shop, and his wife got so fed up she threw him out. ‘But I never lost faith. I believed in him up there, the Almighty. If you do something right he will try to help you out. And that is what happened.’ Last year, Tariq Halal Meat turned over nearly £2.5 million. It employs 16 butchers, has launched a wholesale company and sells its own brand of rice and spices. Customers travel from outside London to buy Tariq’s meat. Soon he hopes to go national.

But Tariq’s business will be finished if the Government accepts the recommendation of one of its own advisory bodies. In June the Food Animal Welfare Council produced a report which claimed that halal and kosher methods of slaughtering animals were inhumane, and should be outlawed immediately. Animal welfare should not, it said, be sacrificed to religious freedom. Many commentators agreed; columnists wrote of their horror at animals ‘writhing in agony’ and ‘gurgling in their own blood’, and animal welfare campaigners came out in support of the FAWC report.

Government ministers are now considering its findings. If they agree, two million Muslims in this country will no longer be able to buy British meat.

‘There would,’ says Tariq, ‘be uproar. It would be like saying to Christians you can’t celebrate Christmas.’

On the face of it, the dispute over halal meat has all the makings of another conflict between Islam and Britain - of competing East-West ideas of what it means to be civilised, of faith feeling assailed by intolerance. But in reality, it has stirred a far more complicated, raw controversy within the Muslim population itself, over its relationship with modern science, industrial economics and even its own clerics. For in order to defend halal, the community has to decide what it means.

In the office above his shop Tariq sits behind a desk and watches the shop’s affairs on a large CCTV screen. He had a heart attack earlier this year, and is struggling to comply with doctors’ orders to take it easy. The screen shows orderly, well-stocked aisles of rice and spices, chutney and dates. There is mango pulp from Gujurat, tahini from Damascus, nougat from Lahore and Heinz baked beans. The meat counter displays lambs’ tongues, liver, kidney, minced chicken, gigantic cows’ feet. At the back of the shop young men from Afghanistan and Pakistan in white coats and hats are trimming, cutting and shaping. Others carry in carcasses on their shoulders. The language in the shop is an exotic jigsaw of London Punjabi, Urdu and Arabic, but the white A4-sized certificates on the wall are in English, and they clearly state that meat for sale has been slaughtered according to the halal ritual certified by the Halal Food Authority.

‘We are very fussy when we deal with the abattoirs,’ Tariq confirms. ‘We don’t deal with any abattoir that slaughters pork. We have a condition with the transport companies that no pork must be carried on the same vehicles as our meat. And there must be a break of an hour between slaughtering halal and non-halal, so there is absolutely no - what shall I say - chance of it being mixed in.’

But what exactly is halal? For the most part, the definition is uncontroversial. The Koran stipulates that the animal must be well kept, fed and watered. It must be alive and uninjured. A religiously trained Muslim slaughterman using a very sharp knife must sever both arteries and trachea, while praying to Allah, and allow all the blood to drain from the body. The only problem is this: pure halal ritual slaughter prohibits stunning an animal before cutting its throat. It must be fully conscious until it bleeds to death. The Farm Animal Welfare Council’s research found that cattle can take up to two minutes to die - ‘and to say,’ its chairwoman scoffs, ‘that the animal doesn’t suffer, is ridiculous.’

Tariq shakes his head sadly. ‘It is far less stressful than the English method. They give big electric shocks to the animal, bolts to the head, sometimes two, three times before it works. It’s horrible. With halal, the blood is drained in a matter of seconds. Listen... ‘ and he scoops up the phone to call one of his slaughterhouses, to ask how long it takes a cow to die by each method. The handset is replaced with some satisfaction. ‘You see? Thirty-five to 38 seconds, English side. Eight seconds halal side. I know for a fact English-style is more stressful.’

He is a gentle, solemn man, and this is as heated as I will see him get. The campaign to defend stun-free slaughter is being led by more voluble members of the community, the Halal Food Authority and others, who have issued public statements denouncing the non-halal practice of stunning, and emphatically demanding their right to religious freedom. They are unequivocal.

Tariq, however, is beginning to look uneasy. He seems troubled about something, and when I ask him to clarify exactly what he means by halal, he looks glum and falls silent.

‘That is a very touchy subject. I have not been looking forward to you asking that. It is a dreaded question.’ He hesitates again, looking uncomfortable. ‘You see, there is a conflict between the mullahs at the moment. They can’t decide themselves what genuine halal is. You’ve got one half saying one thing, and the other half saying another. I haven’t yet come across two imams who are able to sit down together and agree on anything.’

The fact of the matter is that the meat Tariq sells - which is certified as halal - was stunned before it was slaughtered.

‘It’s not as though it’s dead,’ he quickly explains. ‘Stunning just gives you five seconds to get the chain around its leg and get it into a position to slaughter. It’s not like an English stun, it just lasts five seconds, that’s all. At the point that the throat is slashed, the animal has revived. It is kicking.’

So how many Halal slaughterhouses do actually slaughter animals without stunning them at all? Tariq rests his chin in his palm. ‘I could count on the fingers of one hand.’

There is no guilty conscience in Tariq’s shop. ‘We are here as good Muslims. We can only do as much as we can,’ he says simply. ‘Nowhere in the Koran does it mention stunning.’ One of his butchers knocks and enters, lays out a mat on the floor and quietly prays.

But the discrepancy between the public line taken by groups like the Halal Food Authority, and the practice they will actually sanction, has made the whole matter rather delicate. It is a strange and slightly awkward situation. Muslim groups and religious leaders are furiously defending their right to kill an animal without stunning it first. But what none has publicised is the fact that virtually all British halal meat is in fact stunned before it is slaughtered.

Slaughterhouses are not at all keen to discuss their methods. Neither the Muslim-owned abattoirs I contact, nor those serving the halal market, want to talk. Calls go unanswered, messages un-returned. Two receptionists hang up. Bosses are mysteriously called away, or suddenly in Pakistan, or otherwise unavailable.

In Uttoxeter, a tense woman spells it out. ‘Do you think I need the press in here? I’m sorry, but I don’t know how to deal with you. I only get paid £10,000 a year. How much do you think Alastair Campbell gets? And he’s still looking pretty stupid, isn’t he?’

Newent sits in folds of lush countryside at the far western reach of the Cotswolds, a pretty English village of Tudor gables and hanging baskets. On the outskirts, where the cottages give way to pasture, lies a modern-looking industrial estate of glass and steel. At the back of the estate, hidden from view, is Freemans of Newent.

The name is painted on white articulated lorries parked across a massive expanse of yard. There are Portakabin offices beside a stainless-steel factory, and men in white wellington boots and hard hats are coming and going. Through the hum of industrial background noise, a busy air of serious work prevails, but you have little clue as to what goes on inside the plant until you step out of the car. Then the smell hits you - nauseating, putrid and fatty, overwhelming.

Clifford Freeman and his cousin own this poultry abattoir. It is the largest halal plant in Britain, employing more than 250 people, slaughtering 300,000 chickens a week, and after considerable persuasion and hesitation Freeman has agreed to show me how it is done.

The birds are collected from farms at night, transported to the site in the early hours of the morning, and kept in darkness until they are ready to be killed. Workers hang them upside down by their feet in shackles, suspended from a conveyor belt, or ‘line’, which then dangles them through an electrified bath. Their heads are submerged, and a high-frequency current in the water stuns them. The line keeps moving, taking the birds on to the slaughter area, where three men are standing ready to cut their throats.

The slaughtermen are Muslims. Dressed rather like welders, head to toe in protective clothing, they stand on one spot for eight hours with a knife, slashing the throats as they come by on the line while murmuring continual prayer. Being stunned, the birds pass by silent and still, making it an unexpectedly calm and mechanical job. Each man slaughters roughly a bird a second, and the slashing knife, dangling neck and spurting blood form a surreal rhythm, simultaneously horrific and rather peaceful.

The vexed question of what constitutes halal comes down to these few seconds on the line - the period between a bird entering the bath, and leaving the slaughter area. It is a fraction of the bird’s life, but within the details of that six-second process Clifford Freeman’s entire business fortune is contained. Six years ago, his plant was slaughtering only 40,000 birds a week, supplying local shops and small butchers in Wales. Then he was introduced to the halal market in London.

‘I remember that trip we took to London so clearly. I’ll never forget it. I thought, “What the bloody hell have we been doing down in Wales?” We’d been doing maybe 100 boxes to London. Suddenly, it was three artics up the M4 every week.’

Freeman didn’t know much about Islam, so he employed an Indian man from Gloucester to be in charge of recruiting and training Muslim slaughtermen. ‘He’s a very strict Muslim. Slaughtering is considered an important job by them. They have to be a certain... now let me get this right... caste. Your lowest of your low can’t cut.’

Friday lunchtime leave for prayer was introduced, and the line was rearranged so that the slaughtermen would be facing Mecca. ‘That’s not absolutely essential, but apparently it’s good if either the boys or the birds can be facing Mecca.’

Freeman, 38, is a tall, well-set, plain-talking English farming man. Islamic strictures have presented a steep learning curve, that he, his uncle and his father could never have dreamt of when they started the business back in the Fifties.

‘I tell you how crazy this whole thing is. We were building a new toilet block and these guys come in with a compass and say it’s facing the wrong way. We said, “What do you mean?” “No,” they say, “we can’t go to the toilet that way, we can’t be facing or have our back turned to Mecca. Has to be side on.” So we moved the damned thing.’

What qualifies his stunning as halal, he says, is the frequency of the electrical wave he uses. As long as it is high frequency, then technically the birds could recover after about 45 seconds. In other words, when they are slaughtered they may be out for the count, but they are still very much alive.

‘I know some Muslim organisations would rather we didn’t stun. And we tried it, but it just wasn’t practical. And from a financial point of view it’s not acceptable; you know, with all the damage and downgrades. Besides, it’s pretty barbaric really, isn’t it? I’ve heard a few stories about plants that don’t stun. But then when I speak to them they say no, they tried it too but it didn’t work.’

What he does claim to see a lot of, however, are abattoirs approved as halal when they are not even remotely close. ‘Some places, there’s no praying, they’ve just got a tape playing some prayers. Or they cut the birds by machine, not by hand, and just have a quote from the Koran inscribed on the blade. There’s all these little local organisations that set themselves up and say they’ll register you as halal, but they’ll sign up anyone. They’re just interested in getting your money. It’s all about backhanders. But how can they be regulated, if there’s no agreed definition of halal to go by?

‘It’s even worse in Europe. They’re putting halal on the box and there’s been no Muslim killing at all. The French are good, but the Belgians are dodgy, and the Dutch aren’t much better. But then, neither is the UK. The whole thing’s a bit of a bloody mess, to be honest. The sooner trading standards or someone gets in-volved and sorts it out the better.’

Whoever you talk to about halal gives a slightly different version. But everyone insists they have mastered the correct interpretation.

‘Some people seem to have said that as long as the animal is dead it’s OK,’ Dr Shuja Shafi of the Muslim Council of Britain complains. ‘But no, it is not OK. Not if it is stunned. The Koran clearly prohibits any animal which has received a violent blow. Halal meat cannot be stunned in any way.’

Tariq doesn’t want an argument with others of his faith, but that sort of statement frustrates him. ‘I think half the people talking about this have never visited an abattoir.’

And yet Tariq’s own idea of an acceptable solution is dismissed by the manager of a slaughterhouse in Ireland which supplies halal beef to Europe. A nervous, softly-spoken man, he would only speak anonymously. ‘Could we stun a cow only for a few seconds, to get the chain around it, and no more?’ he says. ‘Frankly, no. We couldn’t. There has to be a degree of unconsciousness at the point of slaughter, to make sure there is no suffering. We have to get a balance which satisfies animal welfare on one side and halal on the other, and that means stunning the animal properly before it is slaughtered. What we’d like to see is a situation where our Muslim friends could be convinced that it’s just not necessary to have a pure slaughter.’

His abattoir used to practise ‘pure’ slaughter. It was supplying the Middle East and North African markets, which demanded nothing less than 100 per cent stun-free ritual slaughter. But since 2000, when those regions banned European beef because of BSE, his abattoir has been fully stunning livestock for the European halal market. But if the Eastern ban was lifted and those markets reopened, would he get rid of stunning? He hesitates. ‘Pure slaughter... I don’t know. Speaking personally, I found it difficult myself. Just, er, visually and all that...’

So would he say that the FAWC was right to call it cruel and inhumane? Another uneasy pause. ‘There are a lot of words that are loaded... You can’t use a word like uncivilised, say. That would be very unfair to the Muslim community. But to, um, a sensitive eye, yes it is very uncomfortable.’

However, notwithstanding their different definitions of halal, every meat producer contacted had been approved by the Halal Food Authority. Launched in 1994, the UK’s largest certifying body originally prohibited all forms of stunning, but has since revised its rules to permit types of stunning from which an animal could - were it not slaughtered - recover.

‘Technology has changed,’ explains chairman Masood Khawja. ‘Some people say we have changed our heart on this, but we haven’t. Techniques have changed. It is now possible to stun animals in a controlled, supervised way, and we can be sure that the animal is not already dead when the slaughterman kills it.’

So why doesn’t the HFA agree to the Farm Animal Welfare Council’s proposals? Why not say that the legal exemption from stunning, which Muslims have enjoyed, is now redundant and can be done away with?

‘But maybe in time people will invent some form of machinery where we don’t need stunning any more,’ Khawja counters. ‘So we still want to keep our exemption. The important thing is how we choose to slaughter - whether we stun or not - should be entirely up to us.’

Ultimately, then, this situation essentially comes down to this. The halal meat industry is primarily concerned with what is practical - and pure ritual slaughter is not. The Farm Animal Welfare Council is concerned with what is humane - and believes ritual slaughter is not. There is no real conflict. But for the Halal Food Authority, it is a matter of principle rather than practice - because the HFA cannot accept any proposal which accuses traditional halal ritual slaughter of being cruel to animals.

Nobody seriously expects the Government to change the law. They all agree it would be politically untenable - and are probably right; Defra has already offered assurances that religious freedoms will be treated with the utmost respect. ‘The Farm Animal Welfare Council, if anything, has opened our eyes,’ says Dr Shafi, of the Muslim Council of Britain. ‘It has opened our eyes to the extent that this problem of stunning exists. One just took for granted that the rules for religious slaughter were being obeyed. But basically we’ve found out that the Muslim public is being deceived - being given one impression but a different product, by people who’ve been economical with the truth about how they slaughter. We need clarity and a proper definition.’

He now wants the Muslim community to take a much closer look at the slaughter methods it permits. And so a debate which began with a report condemning the practice of pure halal slaughter might end up resulting in its revival.

‘Our Muslim friends,’ the Irish abattoir manager reflects, ‘say their method of cutting is painless, as quick as a bolt to the head. But who is the scientist who can really answer that question? Until a human being can put his head inside an animal’s head and tell us, how are we ever going to know?’

The value of the global halal meat business has been calculated at £30 billion a year. In Britain alone it is an intricately complex cultural market, diversified into communities who have never even read the Koran or scarcely heard of it.

On a Friday night in east London, Brick Lane glows with the neon shimmer of signs; Mahib Tandoori, Aladin Balti, CafË Bangla. Sweet spices scent the pavements.

Inside, the restaurants are crowded and noisy, with most of the tables taken by non-Muslims. In the Shampan, a group of white office workers from the City consider the idea that the meat they are about to eat is halal. It hadn’t really occurred to them, they say. They probably wouldn’t buy it from a butcher. But who cares?

However, one man, slightly drunker than his friends, has something more to say. ‘How I see it is this, right. I haven’t got a problem eating their meat - whatever it is they do to it. I’m not squeamish. So how come they’ve got a problem eating ours?’ A few of his friends laugh, and tell him to shut up and stop being so stupid. But he doesn’t want to leave it. ‘No, listen. I’m serious now. Just what is their problem?’

To a secular country, notions of squeamishness and animal welfare are still more easily grasped than religious food laws. The concept of halal meat remains hard enough for Muslims to define, but almost impossible for others to comprehend. Mohammed Tariq has never knowingly eaten a piece of non-halal meat in his life. How would he feel if he did?

‘Try to understand, please. It is not revolting. It is sinful. I would feel very, very sinful.’