As many insurers require proof of NCB from your renewal notice, this affects the premium big style.
After 8 calls to Hastings Direct, they agreed to send a letter confirming my true number of NCB (after the policy ceased) and they only stated 6 because this is their maximum bonus.
The letter came today & hey presto......6 years NCB

As luck has it my new insurer (Bennetts) will accept any policy renewal notice within 2 years so I'm ok.
Sorry its been a rant....just thought you should all know so you can check with any possible insurer at renewal time!!!!
ps 4 times I called, they leave you in a que on the phone & when they do answer.....they pick the phone up and imediately hang up!!!!!