There are some places you just don't expect to find a pig, and although I haven't thought extensively before about all the very many different places where I wouldn't expect to find one, if I had, an executive housing estate in Romford would probably figure quite highly.
It's dark when I finally arrive at Tracy Mackness's farm – for reasons which are now obscure, I have decided to go urban pig hunting at 9.30 at night – having negotiated my way off a dual carriageway, on to the estate, through a gap between the houses and down a bumpy lane to a piece of land not much bigger than the plot for an average suburban house and garden. And there, with traffic roaring in the background, are dozens of massive pink and black saddlebacks snuffling quietly in the dark.
The unlikely setting for the pig farm is as nothing compared to the unlikeliness of the pig farmer. Most are born to the business, a few come to it as rich hobbyists. Tracy Mackness took it up midway through a 10-year sentence for her part in a £4m cannabis smuggling ring.
"If you'd told me 10 years ago I'd be spending 20 hours a day working with pigs after going to prison, I wouldn't have believed you in a million years," she says from the portable building that functions as her office (her house is a mobile home parked 10 feet away). "I was a good-time girl," Tracy tells me. "I liked going clubbing and on holidays. That's why I went for the type of men that I did. That's what got me into that mess in the first place."
I have come in search of pork but this is pork with a back story a Hollywood scriptwriter would kill his mother for. After a few years, Tracy transferred to an open prison in Maidstone, Kent, where there was a prison farm. "And I came face to face with this sow and we just looked each other in the eyes and I was hooked. She just looked really pissed off, her babies had been taken away from her that day, and I was really pissed off, I'd gone from being a long-term prisoner with my own cell, to sharing a dormitory with 14 women. She looked at me and I looked at her and it felt like we were both in the same boat."
The farm manager encouraged her to do NVQs in pig husbandry and she worked in a butcher's in her last year on day release. Now, although she has been out just three years, she has set up the Giggly Pig Company, and has 500 pigs, and 20 vans selling to farmers' markets all over London.
It's an amazing story, before you've even got to the pork, although that looks good, too: she gives me a joint of rare-breed shoulder and leg and I drive off again into the dark. It's an exhausting and not very environmentally friendly business tracking down London's urban farmers. I criss-cross the city spending what seems like the entire bank holiday stuck in traffic, wondering why this had ever seemed like a good idea.
Which is also pretty much what Oliver Rowe, the chef at London restaurant Konstam, says when I tell him I'm writing about urban agriculture, and am planning to source a meal from within the M25. "Somebody told me you'd rung," he says. "And I thought, that's what we do every day." It's true, localism is one of food's most fashionable buzzwords these days, alongside seasonality and provenance, and Konstam prides itself on sourcing 80%of its ingredients from the Greater London area.
Its food is wonderful, but Rowe's list of suppliers also includes Southend, Kent and Oxfordshire, and I'm confining myself to the limits of the M25, largely, it seems, to ensure that I sit in the maximum number of traffic jams. But really it's because I can. Every day brings a new discovery. There is so much food being produced in London, in so many inventive ways, some of it on commercial farms, some in community enterprises – there are urban orchards, floating allotments, gardens on the roofs of high-rise estates and any number of things going on in back gardens.
My first trip is to a quail keeper, Ronnie Hudgell in Newham, east London, who turns out to be a 15-year-old schoolboy. He started with some quail eggs when he was 13 which a woman he found on the internet sent him through the post, and he now raises chickens, ducks and geese, all in the not-large back garden of his mum and dad's terraced house. "I tried to hatch out an ostrich," he tells me. "But it didn't work." Which I think his mum, Dawn, might have been secretly quite pleased about.
And on my last day I find myself interviewing Orlando Clarke, a beekeeper, next to a high-speed railtrack in King's Cross. It's already a somewhat surreal experience – he's demonstrating the difference in taste between his Peckham honey and his King's Cross honey ("You see how the Peckham honey is all light and limey whereas the King's Cross one is so much more complex?") – and then Alex Smith, who owns the land he keeps the bees on (it's a garden created in the grounds of a factory depot) asks me if I want to see his vineyard.
Your what, I say? But we walk into a loading bay, and in front of half a dozen men moving boxes with a forklift, there is what is undeniably a small vineyard. "It's a south-facing slope, so it's perfect for vines. Look at this – I only planted that last year and it's grown 12 feet. Chateau King's Cross – we'll have our first harvest this year."
But then, when I speak to Rosie Boycott – Boris Johnson appointed her to be the head of London Food, spearheading the city's efforts to sustainability – she says: "Oh there's vineyards all over London these days. Tooting. Canning Town. Islington." Chateau Tooting, made initially by a group of neighbours in south London, has now grown to become the Urban Wine Company, and in Enfield, at Forty Hall farm, London's first commercial vineyard ("since Roman times," its press materials claim) was planted out last year.
Its wine won't be ready until 2012, and if this is going to be a proper meal there has to be alcohol, but eventually I track some down in a Brentford back garden courtesy of Sara Ward. She writes a blog, Hen Corner ("A little bit of country life in west London"), and her husband Andy tells me how he made a cider press out of "timber and a car jack. Actually, it was a couple of car jacks."
I take away a bottle of their cider – it's strong and sweet and intensely tangy – and then, result!, score a bottle of Orahovac, a walnut liqueur. It's been made by Thomas Parkinson and Roland Phillips who run a website called the London Forager, which has slightly kooky vintage-style films showing you how to make dandelion bhajis and elderflower champagne.
Roland tells me how they were walking past Blackhorse Road tube in Walthamstow and spotted the walnut tree on the other side of the fence. "So we climbed up to get them and that's when the police stopped us. They ran a background check on us just in case we were planning a major terrorist incident."
Did you tell them that you were foraging?
"We did. But they thought we were wallies."
The Wards have a larger London garden than most – it's a corner plot – with chickens and fruit trees, but a major part of Boycott's brief has been to find new gardens, a scheme called Capital Growth, which aims to find 2,012 new growing spaces by 2012. "It's re-thinking what a garden is. A lot of ours are concrete yards," she says.
There's a huge demand for them. Allotments have a waiting list of years, keeping chickens is a fast-growing hobby, although even more fashionable now is urban beekeeping. "I call them the Gucci beekeepers," says Orlando Clarke. "They've got all the new gear. There's even this plastic hive you can get now, the Beehaus, which you buy complete with bees."
And it's not just London, of course. I've picked it because it's where I live, and London Food, the assembly body which aims to support a sustainable food system in the capital, has had a huge boost from the Olympics, but interest in urban food production is happening all over Britain. Manchester now has a comprehensive food strategy. Sheffield, Sunderland, Liverpool, all have urban food initiatives.
They are just drops in the ocean, of course. One of the many unforeseen results of the Eyjafjallajökull eruption was to highlight how precarious our food supply is. Some 95% of our fruit is imported, 60% of our veg. It's estimated 80% of everything that seven and a half million Londoners eat comes from abroad. Forget al-Qaida, a cross-Channel ferry strike would be enough to bring us to our knees.
The Lea Valley in east London used to have the highest concentration of market gardens in the world, and there are still some there, worked by the descendants of the Italians who came to work in them in the 1950s, but many were torn down to make way for housing. In Uxbridge, Duncan Mitchell says there used to be a dozen dairy farms, and now there's just his and one other.
It's another bizarre spot. Just inside the M25, I turn off down a side road and a mile or so on is White Heath Farm, a handsome, ungentrified Georgian building that local property developers must be itching to lay their hands on. The London County Council bought up the land for the green belt after the war and Don Mitchell, Duncan's 85-year-old father, has been here since 1958. The family still rent the land – 130 acres with 120 cows on it – off Hillingdon Council.
"They've been very good, they haven't put the rent up much, but it's difficult to make a living. If we sold the milk to the dairy, we'd get 22p a litre and it costs 25p a litre to produce." Instead they do a doorstep round and make ice cream, and I take a tub of it, and some milk and cream.
Nobody knows exactly how many farms there are in London. In a report, I read that there are 500 but I find it hard to believe. "I find that a bit hard to believe, too," says Rosie Boycott. "I haven't found that many. But they are there. Obviously it's barking to suggest London is ever going to be able to feed itself but there are things we can do to help small producers come to market. And of course a lot of it is about education."
It is, and a lot of urban agriculture is bound up with community action. Seb Mayfield, of food and farming pressure group Sustain, points out that a "lot of community gardening is about social cohesion rather than producing food per se". Which is all very well, but it isn't helping my quest. I go to find a garden created by the artist and architect Fritz Haeg that was commissioned by Tate Modern in a south London housing estate. Haeg champions something called "Edible Estates" and has created a manifesto of the same name calling for America to rip up its front lawns and plant vegetables, but while the garden has been a great hit with the residents, when I go scrumping for my meal (my contact is out) I come away with only a few wild strawberries and some sage. I do, however, score chard and cabbage from just down the road in Lambeth. Richard Reynolds, a "guerrilla gardener" who specialises in "illicit cultivation", sends me directions to a traffic island at the junction of two busy roads, where among the bedding plants I harvest some greens in what, from the looks I receive from various passers-by, looks a lot like stealing.
They don't look the most appetising greens, speckled with dirt and coated with what looks like diesel particles. I'm not sure I actually want to eat them. In Hackney, though, I follow Sara Davies around a plot called Allens Gardens as she cuts the most enticing salad bag I've ever seen: mint, chicory, sorrel, turnip tops, chard, oregano, flowering chives, calendula. Sara works for Growing Communities, a box scheme in Hackney that 600 local residents subscribe to. Most of the produce is from small local producers in Essex and Kent, but they grow the salad themselves on three sites with two paid employees and a band of volunteers.
It's one of the most successful schemes of its type – five others modelled on it are in the pipeline. Unusually for a lot of these projects, it's entirely self-sustaining. And there are hundreds of them, as well as 15 city farms, including Mudchute, the daddy of them all, with 32 acres in the shadow of Canary Wharf. It has allotments too, many of which are gardened by Chinese and Vietnamese people living nearby, and I turn up in the hope of sourcing some pak choi, chilli, water chestnuts… I fail, although Peter Turner, a retired vicar, promises me some rhubarb.
This is handy as I've already picked some rhubarb which I stumbled across, growing wild in the corner of my local park, but it's joined my growing pile of slightly suspicious-looking urban veg. In the end, I cook it anyway. I mix Richard's guerrilla cabbage with some wild garlic leaves I found, add Ronnie's quail eggs to the Hackney salad, cook Tracy's pork and make a gravy with Sara's cider and serve her apple and chilli jelly on the side. Dessert is rhubarb clafoutis made with Ronnie's rare breed eggs, the Mitchell brothers' milk and cream and Orlando's honey, and served with Tom and Roland's walnut liqueur and the Mitchells' vanilla ice cream.
It's not the most sophisticated of menus but it's all from London, give or take the odd splash of oil and a few grains of salt. And it's delicious, it really is, which is no small achievement given my cooking skills. Tracy's pork is succulent, the Mitchells' ice cream is superb. Even the steamed traffic roundabout cabbage tastes like, well, like cabbage. Which might not sound wildly appetising but is possibly more so than steamed diesel particulates. 'Where are your greens from?" asks my friend, Anna. "Oh, Lambeth…" I say. It's all very well knowing where your food is from. But possibly only up to a point.