Fixed it, R1150GS front brake switch
Thanks for your help guys.
I separated the wired connection juntion which is fixed to the frame just below the handle bars on the right hand side.
I checked the resistance to the circuit with my ohm multimeter, and the there was a high resistance ie. 0.50 / 0.60 ohms when operating the handbrake, .should be Zero
I removed the microswitch and wiring from below the front brake master cylinder, then checked the open circuit on the bike with a couple of wires and sure enough the brake light works.
Ichecked the internet and saw that this replacement part was about $60.00. I thought , thats 3 tanks of gas!!
I then decided to pull the wee microswitch apart and clean it up. So I put on my magnification glasses 4x, and if you look very closely you will see that this switch has a little stainless hinged lever, with a very small screw driver lever this clip off, then very carefully use the same jewellers screwdriver to separate the two parts of the switch.
Wow inside is a tiny little spring and a set of contacts. All i did was to get some fine emery paper and sand the contacts which are about half the size of a pinhead, I then squirted it all with CRC cleaner and carefully dried it all.
At this stage before I checked it with my multimeter, sure enough the resistance was Zero.
Fitted it back on the bike, cable tied it all back together and it works perfectly. Zero cost.
This took about two hours to complete, fiddley, but satisfying to fix.
Thanks for your help again.