I might be wrong but as I see it in this case, it is the policy that the no claims is linked to rather than the car(s) and as such it is only the no claims from that individual policy that can be carried on. As i think, mentioned above, it will be the individual policy and number the next insurer will want, and can't be used multiple times. As with any insurance, it's only a problem when you come to claim, so as Ekona says, I'd want it in writing in triplicate and signed by Admirals CEO.
Anyway, congrats on a year of ownership, seems like yesterday!