Had mine done, finally.
I would like to give a big thank you to @brisanmotorcycles. Rapid and friendly service.
It turned out that my old faithful Gearne boots blew out the sole of my left boot as I arrived. Sole just decided to peel off. With a few lengths of 1000 mile/h tape, provided by friendly staff, it was good enough to get me home.
A pair of R3GT's turned up whilst I was waiting. Got chatting and one of the guys started telling how poor his previous experiences with Brisans had been.
I have nothing but praise. The young mechanic who returned my bike was happy to chat and explain what he had done, although I couldn't get anything conclusive about what Triumph had found to be the cause of our brake issue.