So following my previous couple of posts, I finally did it and bought a new IS250 SE MM auto in Cardoxton with Oakham (beige). Had it for a few days - what a fantastic car. Sooo quiet, reasonable fuel economy so far (about 26mpg) close to my old BMW 5-series diesel and a much simpler navigation system -the BMW iDrive system seems so inferior now (although I could dial a phone number on the move!). The Mark Levinson system is nothing short of amazing.
Highly recommend Lexus Bracknell - they've been great.