Hi folks I solved the problem but though I would post up for reference
I ordered a replacement brake switch from flea bay, duly arrived but not until I was under the dash did I see it was wrong, switch supplied was for four wire set up, so duly returned switch and sourced the other one, arrived installed I didn't expect it to work as it was two wire but hey presto job done.
If I press the brake pedal I can just about hear the click of a relay under the dash so somewhere back up the loom is the park lock wiring so must have been the switch after all


What a pig to fit rolling about under the dash cracked a rib on the door cill as I attemted to extract myself from the ungodly position