Any advice on a seal or o-ring between the mater cylinder and the booster??
Have been looking at the protex master cylinder for a MK1 escort (yes I now it doesn't fit) but it looks similar and it shows a square profile o ring fitted on the body that fits inside the master cylinder . Anyone had experience with a capri MK1 V6.
Cheers

Old Capri V6,  my understanding is that there is no seal between the master cylinder and the power booster.  Both these components are sealed individually.  hope this helps.
Regards
John

Yes I agree with the above: I recently recoed my Master and there was no seal there.
 
I was going to put one there, until I considered the disadvantage of not seeing a leaking Master if and when it occurred, when, with a superfluous seal, the leak would possibly fill the Vacuum Chamber, until you'd be alerted by a falling Fluid Level.