Thanks to all for their feedback.
Like afblaster I find the sail really good when it works - it's a shame it broke while I was on holiday!
As an aside, this is a good opportunity to publicly thank the lifeguards at Newport, Dyfed in Wales ... my life wasn't in danger but they were very prompt and very helpful when the sail broke .. for which I am very grateful.
Roger - I wrote to Tushingham at the same time as I posted this thread and they did get back to me very quickly - I've sent them some photos which may help them diagnose the cause, but their response has been impressive so far; I've been the slow one. (Well, I am on holiday)
I'll update the thread when I have some news