I am not far from Petworth and use Bell & Colvill. The guys there, whilst being relatively new to Morgan, definitely go the extra mile to sort out any issues. My +8 was supplied by them and they have had to deal with a few complex issues - which they've done really well. B&C have a very rich history in race preparing Lotus cars, so they are not frightened of any job.
BHM are excellent too - they know more about Morgans than just about anyone. But they're too far away for me (a miserable M25 jaunt) and besides which, I like B&C.
Nick, you are not that far from me - I drive down to Lancing regularly in the spring and summer in my +8. I shall look out for you!