www.jec.org.uk

These don't seem to be generally available, does anyone know where I might find one?

If a master cylinder doesn't turn up, it might be worth finding a brake specialist who would refurbish your existing unit by inserting a liner into it. Mike.

Hi Mike I've heard of a company called Past Parts that do this, so that's an option. The primary piston came out ok so I'll see if I can get the secondary piston out without damaging the bore, if so I might get away with new seals.

To round this off I sent it to Contract Auto Engineering who apparently do a lot of work for Jaguar. Great service and very reasonable at £95+VAT and carriage. You can find them online at http://www.classiccar-brakes.co.uk/

Hope the car is running and stopping well now. Useful info for us all, thanks. Mike.