Thanks for the advice chaps - I'll know in future!
Was a total buggeration. I'm not going to use the car much over winter, I've been gradually going over it with a fine tooth comb starting from the front (wrong end!). Decided it would be a good idea to get it MOT'd so I could occasionally run it out over the winter so booked in for wednesday so put it back together for that. Got a couple of miles from home and it totally locked solid on me, right on a blind junction. Spent a couple of hours waiting for recovery in the rain - not fun, had to stand out on the corner so people coming round the bend didnt smack into me
Could have sworn there was a warning triangle in the kit but now I know better! Couldnt risk taking it home as we werent sure we could get it off the wagon so recovered to a local garage.
Anyway popped over this morning to start taking it apart. It's the offside thats gone - soon as the disk came off the whole kit and caboodle inside fell out. Basically no friction material left on the shoe, it was just worn not delaminated - other side ok. Guess a visual check of the handbrake system isnt part of the service it got a few weeks ago
Worst bit is it's also wrecked the hub, so basically everything outboard of the suspension arms needs to be replaced. Maserati dealer (StAlbans) prices same as Eurospares for hub and bearing assy- anywhere else I should check?
How I wish I'd started the overhaul at the back rather than the front!