Master cylinder by-passing internally, very common.

No idea in your market, but down here, resleeve and rebuild, simple.

 

I have to second Grant Francis.
Mine blew completely when driving on the off-ramp of the highway, doing 90 mph......pedal to the metal, literally....no braking action whatsoever, except for the good old handbrake and engine torque...

replace it all together, it's an easy fix really.
SNG Baratt's has them new for around US$ 125, part number CAC1229
Click here for a direct link

 

Dutch:

Odd that you had nothing for braking other than the park pads. teen little things!!

I thought that the dual master cylinders were for that purpose. Lose two, have two left.
Two caliper braking from 0- still dicey!!!! But, beats none all to h....

Decades ago, I borrowed a company car for a site seeing trip in SOCAL A 68 or so

Comet six cylinder four door. Dear departed and two kids aboard. Malibu Canyon . Picturesque winding mountain road toward the beach. I did go easy on braking. but, brake fade came in!!!! Good pedal, no retard!!! No chaos, they came back as the drums cooled. Would be a great place to "test" my Jaguar .Only 8, not 12, but still quite agile...
Carl

 

Also it could be a sticking caliper piston. On longer trips this heats up the fluid that eventually boils, then when you need the brake, the pedal goes to the floor. I had this on a rear caliper, the ones that don't get much attention.

 

When you are absolutely sure that the mechanics work nicely, the only thing that can cause brake fading is water in the brake fluid.
Brake Fluid is hygroscopic, meaning that it attracts moisture over time.
A fluid change every two years is recommended...

 

Thanks all, it was the master cylinder. Replaced and all working fine.