The world champion Channel hopper

Long-distance swimming: River pilots said it could not be done, but Alison Streeter has defied the doubters

Currency trader Alison Streeter got a call on her mobile phone from her office. "What should we do about South African rand?" they asked. Nothing unusual about that, even though she was crossing the Channel at the time. What was unusual, though, was that she was swimming it.

It happens quite frequently, she says, because she swims the Channel rather frequently. Forty times at the last count, a few weeks ago, a world record. "I always seem to pick a time when the money markets are going crazy. I don't mind, actually, because it gives me something to think about while I'm doing it."

When the phone goes in the accompanying boat it is usually answered by her mother, Freda, who relays the message. Streeter shouts her instructions back across the waves, and ploughs on towards the French coast. Or the White Cliffs of Dover, depending on which way she is heading.

The 37-year-old from Nutfield, in Surrey, has crossed the 21-mile stretch of water more times than any man, or woman, since Captain Webb first did it in his long johns 126 years ago.

The first time was two days after her 18th birthday and since then she's done it one way, there and back non-stop and once three times with just a 10-minute break for a radio interview. In 1992 she swam it seven times in less than six months. Only once has she failed.

"It was my 31st attempt and the weather was really shitty, far too windy, really. I shouldn't have gone, and had to give up. But in a way it was good not to complete it. I was getting far too confident after 30 crossings and here was the Channel smacking me in the face and saying, 'Have some respect'."

Unquestionably, she is Britain's most phenomenal long-distance swimmer. And it's not just the Channel. You name it, she's swum it. Ireland to Scotland, both ways, the Scilly Isles to Land's End, Capri to Naples, Windermere, around Jersey, to and from the Isle of Wight, and around it. Even the tidal length of the Thames, 43 and a half miles from Richmond to Gravesend. And back, which river pilots said couldn't be done.

She's swum with the dolphins along the shark-ridden waters off South Australia and several times around Manhattan Island in New York. The last occasion was just a couple of months ago when she was in a race with Britain's most prolific male swimmer, the journalist Kevin Murphy, who has traversed the Channel 32 times, the most by a man. She has a snap of them celebrating at the top of the World Trade Centre. "Poignant, isn't it," she says. Especially as Murphy is now back in New York reporting the aftermath of last week's atrocity for ITN.

But the Channel, that aquatic Everest, remains the supreme challenge. Some 550 have swum it, which may sound a lot, and a few have perished (one last month), but as Streeter points out, more have gone up in space. "It has a unique fascination," she says. "It is a living thing. You never know what sort of conditions you are going to meet out there."

She has been a member of Redhill and Reigate Swimming Club, where she trains in the local pool most nights, since she was a toddler. "But I didn't really enjoy competitive swimming." Before her first Channel effort, her longest distance was a 14-mile pier-to-pier swim along the South Coast.

She made her Channel debut via the traditional route of Dover's Shakespeare Beach to Cap Gris Nez in 11hr 21 min, facing the cold, the waves and the blackness of the night greased up with a Boots-prepared mixture of lanolin and petroleum jelly. "Now I know you don't need to smear it all over your body. The only way to keep out the cold is to swim harder." A boat and the requisite pilot cost around £1,500 a time. In all, she reckons she has forked out £40,000 over the years, although through sponsorship she has raised £120,000 for various charities. Luckily, she says, she has a good job as a currency trader with Standard Chartered Bank, with whom she started in the City as a teenage work-experiencer. Her speciality is the rand, often turning over a billion dollars a day. Which is why she is always on call, even in mid-Channel. Her three-way trip was accomplished 11 years ago; she is still the only Briton, and the only woman, to have done so, taking 34hr 40 min.

"Looking back on it I'm not sure how I stayed awake. Swimming the Channel is 90 per cent mental and 10 per cent physical. I was so tired I was going to give up after two legs as I'd broken my own British record for a two-way swim but as I stepped out at Dover, only 20 yards from where I'd started 21 hours before, I thought, 'What the hell, let's do it again'." So I stepped straight back in." Not even a loo break? She laughs: "No, you do that as you go along." Like eating and drinking, too. It used to be tuna sandwiches, now it's carbohydrate powders.

Her fastest swim was 8hr 48min, an hour and a half off the American-held world record, the slowest 14hr 24min, which was the last one. "Age is catching up with me."

Has she ever felt in peril? Well, she's been buffeted in the wash of a ferry and tangled up with a bobbing bucket, but generally no. Not in the English Channel. But she almost drowned when making her first attempt on what they call the North Channel, 20 miles from Ireland to Scotland, in 1988. Her ex-schoolteacher mother, who's always with her, pulled her out by her fingertips four miles off the Scottish coast when she became unconscious from the bitter cold and repeated jellyfish stings, and was about to go under. "But for mum I'd be at the bottom of the North Channel. The jellyfish there are lethal. Not like the ones in the English Channel, which you can push out of the way. These buggers swim upside down and come right at you."

She returned two weeks later and did it, and subsequently twice more, one of only a dozen to have made the crossing. Then there's the 29-mile swim from the Scilly Isles to Cornwall, said to be one of most treacherous in the world because of the perpetually turbulent meeting of Channel and Atlantic currents. She did it in 15hr 11 min. No one has ever swum it the other way. "Everyone advises against it, but I'm going to have a crack," she vows.

At 5ft 4in and stocky with it, Streeter is built for battling the waves. Skinny-minnies shouldn't bother trying the Channel. "Women are actually better equipped for it because we have more body fat. You need a bit of blubber to keep out the cold." She lives at home with her parents in Nutfield, but has a flat in Dover, and a bed-and-breakfast place in Sennen Cove, near Land's End, with her boyfriend, a surfer. "We study the wind and the waves together."

Currently, she's awaiting another call on her mobile, this time from Mike Oram, the pilot she has used for 12 years, advising when time and tide are right for her 41st attempt. As we know, they wait for no man. Or woman. Not even the Queen of the Channel.