Normally I wouldn't have worried. Normally it wouldn't have occurred to me that there might be a problem with the afternoon tea being served in a classy central London hotel. But when you are sitting with the country's foremost authority on food poisoning, the man the government calls upon when it needs advice it can trust, it is impossible not to hesitate before picking up an egg mayonnaise sandwich which has been heating gently in front of a roaring log fire. Did he think it was safe? 'Ooh I'm sure it will be fine,' said Hugh Pennington, 'at least for an hour or so.' I took the sandwich but couldn't help noticing that he took the scone.
Hugh Pennington, professor of bacteriology and the newest entrant to the OFM Hall of Fame, is used to this sort of thing. 'In the canteen of the hospital where I worked the chaplains would always hold back to see what I took from the cold buff et before choosing for themselves,' he says. 'I thought it showed a certain lack of faith.'
Still, it's understandable. Pennington, who retired from Aberdeen University in 2003, shot to prominence in 1996 when he was appointed to head up the committee investigating the outbreak of E.coli 157 in Lanarkshire which had claimed 17 lives. Since then, he has rarely been out of public view, be it criticising government inactivity over avoidable food contamination, identifying the causes of the BSE crisis, decrying the filthy habits of Britain's growing legions of celebrity chefs or handing out advice on cleanliness in the domestic kitchen.
In the process he has become that all too rare commodity: a scientist who can make science understandable; a communicator who can deal in big, sometimes unpalatable ideas. 'A lot of scientists don't see it as their job to do this sort of thing and they're scared of the media,' he says. 'They want to get on with their research. They don't want to jeopardise their grants.'
Pennington, a political animal by nature, is made of sterner stuff. Ask him to name the high points of his career and, mischievously, one of them will be the moment he said 'bollocks' to John Humphrys live on air during Radio 4's Today programme after the interviewer had suggested, in his usual gruff manner, that we are too hung up on cleanliness.
Pennington thinks we are nowhere near being hung up enough. After all, an estimated 500,000 of us suffer food poisoning every year and it doesn't just happen by accident. 'The Humphrys thing was odd,' Pennington says now. 'I expected him to come back with something but he didn't. In fact I keep expecting to get myself into trouble with what I say to the media but it hasn't happened yet.'
Certainly he is unafraid to speak his mind, in a way that has sometimes won him enemies. At the top end of Britain's food world, which has come to associate organics and therefore 'naturalness' with sometimes spurious notions of purity, a professor of bacteriology telling it as it is, may not always be welcome. As he explains, E.coli 157 is a dangerous contaminant spread through animal faeces, which can kill the very young and the old, and shit is still shit whether it comes from an organic animal or a non-organic animal.
He is absolutely not against the organics movement or the doctrine of local producers, both of which he says are admirable and all to the good when practised well. But he won't shy away from the harsh realities if he feels they need to be exposed.
'Not long ago I had a great row with Clarissa Dickson Wright who is Rector of Aberdeen University where I held the professorship,' he says. 'A child had died after picking up an infection from animals while visiting a children's farm and I was arguing that precautions had to be taken with small children in the countryside. She just saw this as over-cautious nonsense.'
None of this resistance to his arguments surprises Pennington, whose skills as a scientist and communicator are buttressed by a terrific grasp of history. 'In the 1930s you heard exactly the same sort of outrage over the pasteurisation of milk. Food people would say that pasteurisation stops the milk being natural. That it's just town people trying to regulate the country, which they don't understand.' Then he adds 'of course between the first and second world wars it's estimated that over 60,000 people died as a result of illnesses contracted through drinking unpasteurised milk'. Against statistics like that, theories of naturalness and whinges over meddling townies quickly wither.
Talk to him about the oft-derided modern factory farming methods and you get a similar historical analysis. 'If you look over the 20th century, at the beginning lots of kids got diseases that we don't see any more. There was lots of symptomatic tuberculosis because they were not eating an optimal diet. There was also rickets, again due to diet. Things like cheap chicken have solved that problem.' Of course, he says, there is a downside, including the spread of bugs like campylobacter and mass-produced salmonella. 'Though if you look at it brutally and over the long term it's not a bad trade off .' In short, the benefits for public health of factory farming far outweigh the downside.
This, the long view, is the key to Pennington, who is 66. He started his career at a time when many of the vanquished diseases and illnesses of today were still killers. The professor who mentored him in microbiology in the 1960s had himself been mentored by Sir Alexander Fleming, one of those responsible for the discovery of penicillin, the first great antibiotic wonderdrug. As a doctor Pennington saw children who died as a result of measles and, when he attacks those responsible for the unfounded scares around the MMR vaccine, his arguments are informed by that experience which is burned on the memory. In short he is a bacteriologist and microbiologist first who happens to have found his way to a specialism in food contamination.
'It was essentially because I became interested in using advanced methods to fingerprint certain bacteria,' he explains. 'In 1991 when the Scottish office wanted to set up an E.coli 157 reference lab, a place which could reliably be used to identify the bug, we got the contract at Aberdeen.' E.coli 157 is a virulent if relatively new organism which causes an illness much like dysentery.
The first cases of human infection only surfaced in England and Scotland in the early Eighties, though their numbers have increased in recent years, particularly in Scotland. It is known that livestock are the main reservoir for the contaminant, usually through their faeces, and that it takes a very small dose to cause illness in humans which can result in kidney and brain damage, if not death.
The 1996 Lanarkshire outbreak occurred after a church lunch of steak pie (with a contaminated gravy) was served to pensioners. As the bug can be passed from human to human, around 500 people were soon infected and dozens were hospitalised. 'And of course it was killing people,' he says, 'which was politically unacceptable. For some reason if it's older people who die in a situation like this it has a greater impact.' This is one of Pennington's pet subjects: the way politicians react to science-based incidents. His report into the E.coli outbreak, which called for a mass education eff ort in food hygiene from primary school level upwards to the meat trades business, also recommended the licensing of butchers. It took three years to be implemented, as politicians in Edinburgh and London argued with each other.
'The political establishment has a real problem over how to deal with science,' Pennington says. 'They like to have their experts and once they've appointed them if anybody says anything diff erent to their advice , they get ignored.' But science doesn't work like that. It's not a set of black and white conclusions, but a slowly reached consensus among a group of disparate individuals. What's more 'the consensus isn't always right'.
This, he says, was why the Conservative government tied itself in knots over the BSE crisis. The government-appointed Southwood committee, under Sir Richard Southwood, concluded in the late 1980s that BSE was like scrapie in sheep and that as scrapie had never infected humans BSE wasn't a problem either. 'Less attention was paid to Southwood's caveat that if they were wrong the implications could be serious, mostly because the committee itself had not placed enough emphasis upon those warnings.' It would take many years for the link between BSE and New Variant CJD to be made. 'Politicians have to make decisions but most of them are not in a position to make those decisions.'
As an example of the establishment's failure to understand science he points to the case of cheese maker Humphrey Errington. 'In 1994 I was an expert witness for Errington. A blue cheese he had produced was found to contain listeria so it had been confiscated and he was being prosecuted for selling it. But not all listerias are dangerous to everybody. On that occasion I was speaking on behalf of the small producer. The cheese was safe enough and if you like that sort of thing I felt you should be able to eat it as long as you understood the risk.' Errington got his cheese back.
This plays against the way Pennington is sometimes caricatured as a man who is entirely risk-averse and wants us to be risk-averse too. Risk is everywhere. We just need to understand what those risks are. For example, though he does not describe himself as an all-out foodie, he does profess a fondness for sausages which, with their pig intestine skins and sometimes 'interesting' contents are, he admits, not always that great 'from a public health point of view'. Still, it's hard to fight a taste for the mighty Cumberland.
On other issues though he can be uncompromising. He has railed against the presence in the kitchen of the tea towel which, he says, can be a massive source of contamination. He's not fond of the washing-up bowl either and argues that, if you really want to get your dishes clean you should use bleach and hot water. Not that he has been too successful in getting this one across. Even his wife is yet to give up her tea towel.
No matter. Pennington is an educator and he's not the sort to be distracted from his cause by a little domestic resistance. He describes himself, quite simply, as 'pissed off ' that, by the terms of his contract, he was forced to retire from Aberdeen University in 2003 when he turned 65. Then again, it's impossible to retire from the intellect, and he remains very active in his field. He's a member of the Food Standards Agency's Scottish Food Advisory Committee. He sits on the BBC Rural Aff airs Advisory Committee, is director of various research institutes and a regular contributor to the comment pages of newspapers both big and small. And now he enters our Hall of Fame, and rightly so. He's a national treasure. Plus, he was spot on about that egg mayonnaise sandwich. It didn't cause me any problems at all.
· Jay Rayner's novel, The Apologist, is published in paperback price £7.99