FOUND IT!
Turns out, Renault Arsehole Clark Stirling detached my brake master cylinder when my ignition/injection computer went bang.
Singlespeed and I did a little digging about tonight.
The Reservoir was left dangling (cap down) on top of the gearbox...no sign of the fixing bolts or anything!
I'm gonna reattach it tonight, even if it's with Cableties as a temporary fix...you know..to get it out the way of the hot Exhaust Manifold!!!!!
Pissed off doesn't describe it!