When I got my new car I was usurer under my old one with aviva, I had 3 weeks to go to get 1 years no claims, I bought the new car and rac were offering me 64 a month for 1 years no claims, so I took it but had to cancel immediately at aviva, I phoned up and they said that my years no claims would still stand.
However... 3 weeks later I got a letter saying that I wouldn't be getting my years no claim as I never re-insured with them. One angry phone call later and they still refused even though I had an email saying I had a years no claim, contacted rac and they let me continue with the years no claim insurance.
In short don't trust any insurance company.