Property correspondent Peter Trevail discovers that livestock thrive in the shadow of London's tallest building, but you'll need a fat cheque book to buy a city house with land.

A young lady from the Smallholder marketing department, who is responsible for posting copies to monthly subscribers, asked me why so many people in London read the magazine.

"Surely they can't be smallholders if they live in London," she said. "You can't keep farm animals in a city."

Well, there are two reasons why Smallholder has a large number of readers in London and, indeed, other major cities around the UK. The first is that there are many city dwellers who aspire to become smallholders, and like to keep up to date with farming issues. The second is that, contrary to popular belief, urban smallholdings do exist and are thriving.

There are, in fact, 15 city farms in London, the largest of which is within the shadow of London's tallest building at Canary Wharf. The smallest, at just under an acre, is overlooked by the spooks at the MI6 offices near Vauxhall, on the south bank of the River Thames.

Admittedly, these city farms are mainly educational establishments, run as charities rather than private enterprises. But, as Tom Davis, manager of Mudchute Farm, will confirm, there are many individuals in London who are smallholders.

"Upwards of 20 people from Greater London have bought hens from me," he said. "Keeping poultry seems to be a growing trend in the city."

It is, of course, important to define what a smallholder is. I met an exhibitor at last year's Smallholder Show in Builth Wells who keeps pygmy goats in the back garden of his council house.

And millions of people no doubt watched TV chef Gordon Ramsay (with advice from Smallholder columnist Janice Houghton-Wallace) raising turkeys in the back garden of his London home during his pre-Christmas Channel 4 F-Word programme. Would he regard himself as a smallholder? Probably not, but there are many others with a garden the size of Gordon's who might.

The truth is that anyone with a piece of land large enough to grow vegetables, keep poultry or rear some small rare breeds can call themselves a smallholder. You don't have to be dependent upon smallholding for a living to be part of this fast-expanding community. Everyone has to start somewhere and a large back garden in the east end of London is as good a place as any.

Having said that, finding a city smallholding for sale - my brief for this issue - is another matter. None of the many property web sites that I looked at had any search option available for a house with land. You could tick how many bedrooms you require, the number of parking spaces, the price range or even the post code. But no tick box for land.

Searching through the hundreds of city properties available for sale on-line, and reading the descriptions to see if there was anything resembling a large garden, was like looking for a needle in a haystack. I therefore had to take the old-fashioned route and pick up a telephone - and the conversations I had with some city centre estate agents must have sounded like something from a comedy sketch.

Me: "Good morning. I am looking for a house in London with some land so that I can run a city smallholding."

Estate agent: "Sorry, sir, we don't deal with development land. Only residential property."

Me: "Yes, that's what I want. A residential property. One with a large garden that I can use as a smallholding."

Estate agent: "A small what, sir?

Me: "A smallholding. I want to grow my own vegetables and keep some chickens."

Estate agent: "I've got a nice three-bedroom apartment in your price range, sir. It's very close to a large Tesco and they always have a good range of vegetables and chickens."

No, I made-up that last bit! But you could almost read the mind of the person on the other end of the line. Why would anyone want to grow their own vegetables and keep chickens when there is a superstore on every corner? I was written-off as a nutter!

The truth is, there aren't many people looking for a house with land in London. And even if you found one that was suitable - and I didn't - the price would be rather ridiculous. You would be competing with the likes of Roman Abramovich for some of the properties I found for sale!

The nearest I came to it was a semi-detached house with two-and-a-half acres in Carshalton, about 12 miles south of the city. This "semi-rural" property, with outbuildings and greenhouses, had a guide price of £550,000, which seemed quite reasonable for the size and location, which is probably why it was already under offer.

There must be an opening for an estate agent who can specialise in city houses with land attached. Or even one with a web site that allows "land required" or "large garden" as an internet search option.

So how much land would be needed to make a smallholding worthwhile?

The Vauxhall City Farm has five horses, a Red Dexter cow, two goats, two pigs, a sheep, various chickens, ducks, geese, rabbits and ferrets, plus ten allotments - all on three-quarters of an acre.

The farm, at Tyers Street, Vauxhall, is opposite Spring Gardens, a public open space, where disabled riders exercise the horses and the animals are allowed to graze. Two full-time and four part-time staff, plus a lot of volunteers, run the project.

Mudchute, the largest of London's 15 city farms, covers 31 acres on the Isle of Dogs, within site of the vast Canary Wharf skyscrapers where national newspapers and world-leading financial institutions are housed within the world's biggest commercial development.

The farm has a wide variety of animals including goats, sheep, llamas, pigs, horses, cows, ducks, geese and dogs. There is also a BHS-approved equestrian centre, an education centre, garden centre, shop and cafe.

All of the London city farms are registered charities and they provide educational and recreational services, working especially with local schools.

The city farms all help each other and together form a thriving inner-city smallholding community.

So, if you're wondering what to do with that extra large back garden, take a trip to Mudchute or Vauxhall to see what is possible. And if you already run your own inner-city smallholding, please drop me a line and tell me all about it (see contact details on page 3).