When Karen met Callie

Behind every great book is another story entirely, and I thought you might like to hear ours. If I had a pound for everyone who has told me I really should write a book about their life, I would now be reclining on my superyacht in a Heidi Klein bikini in the middle of the Indian Ocean.

So when I took a call one sunny Sunday morning in June two years ago from my lovely and very well meaning mother in law about a new book idea she had for me, I was a little sceptical.

Jean volunteers as a community car driver, ferrying people who can't drive themselves to and from hospital appointments. She had been chatting to a lady called Julia as she drove her to hospital. Julia was talking about her grandson Deryn and the remarkable recovery he was making following several years of illness and how much his mum Callie would like to write a book about him.

'My daughter in law is a writer and journalist, she's just written a book, maybe we should put them both in touch?' Jean volunteered. Julia agreed that it was a great idea. Jean could hardly contain herself and told me it would definitely be a bestseller. We chatted for a while longer and when she hung up, I went back to devouring the Sunday papers.

I couldn't get Deryn out of my head however, so I started checking out his story online. Sure enough, it stacked up to an amazing tale, a real triumph over tragedy which had already attracted quite a few headlines in the local and national press. I emailed Callie that afternoon to ask if she fancied having a chat about the possibility of working together on a book. She was overwhelmed and told me she had been waiting for something like this to happen. It seemed almost too serendipitous to be true. We kept in touch, and planned to meet up later that summer while I was visiting family in the UK.

I'll never forget the first time I saw her. We had arranged to have lunch together at a gastro pub in a small village near her home in Watton. I didn't really know what to expect but I had a warm feeling inside when this exuberant yet nervous bundle of smiles with bright pink hair walked towards me. Several hours later, we were still sitting there, my dictaphone running as she relayed the most amazing story of Deryn's incredible battle for survival to me. It's fair to say I was hooked from that moment.

She took me to meet her lovely mum Julia and a somewhat shy but utterly charming Deryn, together with his little brother Dylan and I drove back to Jean's that evening feeling like something pretty momentous had happened that day.

Callie and I knew we had an amazing story to tell but we had no real idea at that stage just how much it would captivate the rest of the world. All we knew was that it needed to be told, frankly and fully with no punches pulled, and that it might, just might, change attitudes towards alternative treatments for pain relief and critical illness. It was a huge risk for her to tell the story as honestly as she has done but it was never an issue for her.

You will have read, heard and watched much over the last 12 days about Deryn's inspiring and courageous story of survival but there is so much more to the The Boy in 7 Billion than the headlines and news stories of the last week or two. It's on sale from today so if you happen to walk past a Smiths or Waterstone's, please pop in and take a picture of it on the shelf for me.

Serendipity, fate, a miracle....call it what you like, one thing I can tell you is that this book will restore your faith in hope, human nature and the goodness that is all around us if you look hard enough.