When two mums decided to ask celebrities for their favourite jokes for a book to raise awareness of life-threatening food allergies, they were overwhelmed by the response.

One of them, Ruth Campbell, reports on how they raised a laugh.

'MUM," Patrick shouted upstairs, "Lambeth Palace just phoned. I think the Archbishop of Canterbury has a joke for you." There can't be many schoolboys who have taken a call like that.

If he sounded a bit blas, it was probably because he had become used to me chatting on the phone in our kitchen to everyone from Ronan Keating's agent to the Prime Minister's office while he and his brothers had their tea.

Myself and Elizabeth Metcalfe, another mother at our small village school in North Yorkshire, were appealing to leading politicians, sports stars, musicians, comedians and actors to help create a Favourite Jokes book for charity.

Three out of 100 pupils at Fountains primary school, near Ripon - including my son - suffer from life-threatening food allergies and we wanted to draw attention to the condition, known as anaphylaxis.

For Elizabeth, who also has anaphylaxis in her family, and I, bagging another celebrity in between school runs, work and children's tea and bath-times became an amusing, almost addictive, pastime.

But, most of all, we wanted to educate the public about anaphylaxis. Although it is on the increase, it is manageable and, as long as people know about it and what to do in the event of an emergency, most deaths are easily avoidable.

After years of being faced with blank stares while explaining to people in cafes, supermarkets and at children's parties about my eldest son's allergy, I know how vital it is people are made more aware of the problem.

At first, getting jokes wasn't easy. Celebrities are inundated with appeals to help good causes and, understandably, can't act on all of them. Annie Lennox's agent told me she gets as many as 40 requests a day, from all over the world.

I literally punched the air when the king of cool, David Bowie, sent us a joke. Once we had someone of his stature supporting our book, it was easier to get others in the music industry to listen. Although we laughed when the agent for one international pop diva, while helpful and sympathetic, said it wasn't worth asking his client for a joke because she didn't have a sense of humour.

Throughout the months we had to beg, plead, phone, fax, write and email, and use all our powers of persuasion. We told each of the political parties we were sure to get jokes from all the others and, for the sake of balance, urged them to take part too.

It seemed to work. We even got a joke from the Prime Minister. And, while some politicians, understandably, told us they were much too busy to think of a gag, we were impressed when the then Tory leader William Hague sent us one, personally signed, in the middle of his general election campaign. "Good luck with the book," he wrote.

Chancellor Gordon Brown, clearly not as dour as he can appear, was quick to respond and Edwina Currie, now famous for being the ex-lover of former Prime Minister John Major, even quipped that hers was "one of the cleaner jokes I know".

Some of the jokes aren't particularly funny, at least to us. But even then, they are very revealing about the person who sent them. And a few celebrities originally sent the same jokes. Who would have thought that Gary Lineker and Michael Parkinson, Iain Duncan Smith and Richard Whiteley, Laurence Llewelyn Bowen and Denise Van Outen and Carol Smillie and Dr Hilary Jones were comedy soul mates?

From our own very ordinary family homes in rural North Yorkshire, we soon caught a glimpse of a much more glamorous, jet-setting lifestyle.

Stephen Fry was just leaving for Peru to make a programme when Elizabeth nabbed a joke from him. And TV presenter Michaela Strachan thought up her gag as she chatted on her mobile on her way to catch a flight to Africa where she was filming.

I had to contact one rock star on tour on the other side of the world to ask, ever so politely, if he wouldn't mind us changing a rude word in his joke and ended up locked in a hilarious email dialogue which was actually much funnier than his original gag.

I did even write to one of my comedy heroes, Woody Allen. He didn't reply. But one morning I got a letter from comic legend Ronnie Barker, beautifully hand written in fountain pen: "Herewith the shortest sketch I've ever written! It's for your favourite jokes book," he wrote. As one of his biggest fans, that is one I'll always treasure.

And my mother-in-law nearly choked on her cup of tea when she answered our phone to hear a familiar, clipped voice: "Hello, this is Kate Adie." The famous foreign correspondent went on to add: "I work for the BBC." "She didn't need to tell me that," said my mother-in-law.

In the end, more than 100 famous people kindly contributed. We hope the book will make people laugh. But, by raising money for the Anaphylaxis Campaign charity and drawing attention to the condition that affects up to a million people across the UK, we also hope it will help save lives.

* The Anaphylaxis Campaign, PO Box 275, Farnborough, Hampshire GU14 6SX. (01252) 542029. www.anaphylaxis.org.uk

* Favourite Jokes is available direct from the publishers (£4.99 plus £1 postage and packing) Great Northern Books, Midland Chambers, 1 Wells Road, Ilkley, West Yorkshire LS29 9JB (tel: 01943 604027), or from any good bookshop.