So, Ithink i might have this figured out - finally!
Esure (my current insurers) can start a new policy with an intoductory offer of 3 years NCB. That policy would then just run as a seperate policy and start to build it's own NCB.
However, Esure require 5 years NCB for an Elise. To get around this I can switch my main policy (which has over 10 years NCB) from the Clio to the Elise and use the introduction offer for the Clio. Doing this means that I'd be charged a total off £480 to switch the policy to the Elise and start a new on for the Clio (the breakdown being £350 for the new Clio policy & an additional £120 on my main policy to switch from the Clio to the Lotus).
For reference REIS quoted me £850 for the Elise (obviously has the benefit of TD cover) Manning were north off £1000 and I havent had a chance to get hold of CCI yet.
Just need permission from the boss to buy the car now!