Hi Guys,
Just to let you know, with most Insurers your NCB is valid for 2 years since the date your last policy expired.
If your expiry (cancellation/renewal) date of your last policy is within 2 years of when the cover is required it's likely that most companies will accept it.
Presumably the comparison site will either ask you when your last policy expired, or make an assumption in this regard. Which should be listed upon their site somewhere or your application.
Failing this, click through to check the respective Insurer/broker's deal, then call them to clarify.
Kind regards
Tony