Can anyone please help me out?
The alternator light on my 75 bay keeps coming on. At first it was intermittent, now it stays on unless you press the brake pedal.
Also when the lights are on the brake lights dont come on when you press the pedal ( and the engine wont switch off - holding the key in your hand with engine on is not a good thing!!!)
Advice please?!

get along to your local Auto Electical guy

he can check out the voltage output of you Alternator and advise from there

Sounds like the inbuilt regulator or diodes r gone

its NOT something in the wiring unless u have been fiddling in there

you have an earth problem eather the breaks or the lights i had this same thing and it turned out to be the earth wire on the rear light cluster on the drivers side
what happens is the electrisity will find an earth by going back throiugh wires until an earth is found and that could be any light any light warning or tail lights
good luck