OK thanks for that, I think I will need to get this looked at by someone as I could go on forever throwing parts at the car, and not really getting anywhere. I am certain that the problem is aux' belt related, all tensioners and the belt itself have been changed, which surely leads to the following problem areas...
Power Steering Pump
Crank Aux Pulley
Air Conditioning Pump
The air con' pump cuts in and out when turned on and off, and no unusual noises when this is fully running. The power steering is quite noisy anyway (I think - maybe they all sound noisy on the 156!) However, even with everything turned on, things such as heated rear window, all lamps and main beam, air con, fans, wipers etc - basically with everything loaded on the belt, this doesn't alter the noise - only in the wet when it doesn't exist!!!! Aarggghh !!