More nightmares with the brakes. The rebuilt master cylinder kept sticking so I removed it and found the secondary seal was too dry. A liberal coating of grease sorted that. Refitted it and was trying to bleed the system when after a few mins of using a vac bleeder and pumping it locked up solid. I'm talking mechanically not hydraulic. It's at that point that I decided that it was too cold to think, locked the doors and came inside. Will have a look in the morning.