I'm on a 9 month rapid bonus policy with Norwich Union and they've been brilliant.
Always give me the cheapest price at renewal time, and they always come up trumps when I phone up to say can they help on getting it cheaper.
I protected my no-claims as soon as I got to an equivalent of 4 years NCB (after 36 months) so won't loose it now. Glad I did as well, had a total-loss accident 3 months after protecting but even so, still only paying £325 for 9 months on my Mk5 1.9 TDI. Bargain tbh. I'd recommend it to anyone, even though the rapid bonus doesn't seem to be transferable.
The trouble is that as a young driver, most insurers can't give more no-claims that you could have been driving, so be they will do is match the number of years driving.