It's a Ford Focus, the brakes still work (in the most basic sense, they stop the car), the discs and pads are both relatively new, the whole system was recently bled with new fluid.
But when I hold my foot on the brake with the engine running the pedal sinks down. I can pump the pedal and it firms up. If I hold the pedal while the engine is off then it doesn't seem to 'sink'.
I can't see any fluid leaks and from the level on the reservoir it doesn't look like any fluid has been lost.
So is this normal, or is there likely to be a fault somewhere? (master cyclinder?)