Brakes...not done. New master cylinder Sir?

OK...so I changed the pads @the weekend having earlier swapped the fluid and bled the system. It's clear the RS42's (pictured) were glazed; "yay" I thought.....brake-balance cured! Sadly....
'twas not to be....

Rather than sand-papering the RS42's (I'll leave that for another day) I wanted to get a new set on the car all-round so to reduce any scope for variance. So, with a new set of Carbone Lorraine's installed (pictured below) I set off on a hopeful test drive, expecting that magical feeling of front-end-bite to return.
Pads bedded-in, I go for a few hard-stops. It went like this:

Brake> rears lock > dab of oppo > Try again.
Brake > rears lock > dab of oppo > try again. Merde!



Net/Net....the "tiny job" I expected is the sting in the tail. Rad, clutch, rear main seal, toelinks, misfire, coilpack....and now I need a new brake master cylinder and/or a caliper refurb. All before silverstone. Super.

I reckon the cost per lap YTD is something like £1,000 ...presently. This is really rather not going to plan.