Hi I'm hoping someone else has experienced and solved this problem,

My L reg (1993) Pug 106 1.4XND blew a headlight last night and a couple minutes later that side of indicators started flashing quickly as if a bulb was out, which it isn't. Everything works fine without the headlights on but once they are the brake light on that side fails as does the rear indicator?!

Can anyone explain??

I cannot find a schematic for your model, but it sounds like a faulty bround circuit.
I've also seen a bulb not appear to be bad but one of the elements had broken and contacted the other element, shorting it not to ground but feeding back through the other circuit.
Try installing a redundant ground to see if that helps.

Solved the problem - turns out it was a fault with the connection to the rear cluster, by simply disconnecting the plug on the inside of the boot and reconnecting it