Jay has always envied her cousin Delphine. While Jay was brought up in a large, noisy and chaotic family, Delphine was indulged, perfectly dressed with a co-ordinated bedroom, an immaculate wardrobe, dancing lessons and monogrammed silver-backed hairbrushes. Now Jay lives happily with her architect husband and their three teenage children, running a successful cleaning company and trying to keep some kind of order on her disorderly household, while Delphine has long since disappeared to Australia with her second husband. But Jay does sometimes wonder whether she should be more like her cousin - utterly well-organised and with a size ten figure.

So Jay decides to diet. But what should it be? High carb, no protein? High protein, no carb? High fibre? Wheat free? Fat free? Food free? She tries them all, with a variety of successes and failures. But then Delphine reappears, with a third husband in prospect and the same old air of apparently effortless superiority. Jay never considers that perhaps Delphine is the envious one...

You could assume that there's pretty shallow and unimportant subject matter here but anything to do with diets can't fail to hit a chord with almost any woman. I think when I wrote this I was feeling two things: a) a bit fat and b) overwhelmed by the constant in-your-face pressure to achieve some kind of perfect body shape. So I made Size Matters very much a social comedy with food fads thrown in. Obviously I tried all the diets.. and all of them work if you've got the discipline. I seemed to lack that bit and put on half a stone. But then if you've got the discipline a simple do-more-eat-less is all anyone needs. The Perfect Cousin was easy - my childhood was spent very much in awe of my own princess-cousin. It would have been easy to loathe her, but she's actually brilliant.