As promised herewith is the solution to a non functioning rev counter. Having travelled to Speedy Cables and tested the unit it worked. They knew what the problem was and it was down to the two white wires being connected the wrong way round. The problem lay with the new wiring loom . The two white wires have a coloured trace (one with red and one with black).The wiring loom rev counter plug corresponded with the rev counter plug BUT the coloured trace was on the wrong wire. Once back home a quick swap of the wires and bingo - brilliant. Apparently the current has to flow in a certain direction for the coil to register the pulses and if sent in the wrong direction it wont work.
The wiring loom was the cause all along and there was no need to have it repaired.The end result was at a cost and a lengthy time off the road. For those fitting a new loom - be warned ! I will be addressing the so called loom company at Stoneleigh next Sunday but i doubt if i will even get an apology.