More good ideas guys...
To answer some questions helpfully posed along the way:
Graham - I don't want a classic, I've got three temperamental cars already and I'm not sure I've got the temperament to cope. I want a 'just get in and drive' - but with some excitement.
David/Brian - funny you should highlight McLaren, I have been looking at these - a late 12C & Spider especially. The swoopy front intake/headlights of the more recent models isn't my thing. I know it should be about more than looks, but I'm not sure I'd ever use the increase in capability of the later cars. Downside; £5k a year on a factory warranty on a 12C !!!
But there's so much other exciting stuff out at the moment, from Alfa, BMW, MBAMG, Aston - Geneva will be fun this year.