Brake warning light and soft brake pedal

[Webgen]

Hi
My wife and I were driving back from Suffolk to Worcestershire today and the brake light warning light came on, first check was was the hand brake on - No. Second check was the brake fluid low - No.
Next read the manual and this stated that this light comes on if a) the hand brake is on and b) if there is a brake circuit failure - there are two.
The brakes can be pumped and firmness returns to the pedal but this disappears again fairly rapidly.
Can someone please suggest the correct route to find the issue.

Thanks
Mark 
 

[KateLovesPurple]

Sounds very much like a cylinder failure, or flexi leaking. Have a look at your rear drums for damp patches, same for the flexi pipes on all four corners. If you don't see anything you might need to take off your rear drums and look for damp inside. If it is a rear cylinder, then you will likely need new shoes as well as they will soak up any leaking fluid.

[Webgen]

Thanks for the reply, I have come to the conclusion that it is probably the master cylinder and am going to jack up the beast today and inspect for leaks first.

[KateLovesPurple]

Could be, especially if the level isn't going down.

[Webgen]

I've checked all the pipes and brake cylinders (even removed the drums on rear wheels) are none are showing any leaks so a new master cylinder has been ordered and hopefully this and a good bleed will resolve the situation.
Thanks

[Schnippzle]

On my 83, the copper pipes had started to leak in a few places so had to rip them all out and have some replacements made.  Not a difficult job, just filthy and brake fluid isn't the nicest of stuff at the best of times.

If it's "just" the master cylinder then you're in for an easy win