just spent all day under the bonnet checking out the bits you all suggested.Could not find any loose or faulty wires, connections or anything out of the ordinary.Took it for a 40 mile run with my friend following (with the tow rope) just in case. Sods law it ran perfectly.
What I have just discovered 1/2 an hour ago when I decided to check the earth on the ECU (after finally gaining access) was that the "plenum chamber" (I think it is called) in which the ECU is housed, had about 3 to 4 inches of water in it as the drain hole was blocked solid. I have now cleared the blockage and am about to get the hair dryer in to dry things out a bit. I have no idea if this will solve the prob or if it has done any damage, only time will tell but I would urge you all to check yours NOW as I think this could prove to be very be expensive. I hope this will be of some use to someone.
I am most grateful to all who replied to my post, this is a great site. Thank you. Will report back in a while and let you know if this has solved the prob.Take care, and get your drains cleared !!!