so thought, yes this needs changing 
so took all 4 wheels off, undid all the bleed nipples, ok i suppose i don't need to tell you good people how to change your brake fluid lol anyways for about a week the car was mint, pedal was good, brakes were good, again.Till about a week ago. I have checked the fluid again and it's mint but the pedal travel is too much! It doesn't go to the floor but it's like it's losing it's vacuum! When you turn engine off the pedal becomes immediately solid but this from the position of the pedal when the engine is running, which is about half way to the floor from being driven.
The pedal immediately starts to do this upon being driven though from engine off to on the system will pressurise until it's driven
I am stumped cos surely if the master cylinder was faulty the pedal would remain solid even when driving?
There is no leaks