I would have had it booked in a garage by now . Mike
It was the garage that told me it was the serpentine belt!!!
BTW thanks for the reply Ian101
Sometimes the noise is continuous screeching sometimes just a chirping or ticking sound every second or so.
Someone told me it was the water pump someone else said some combos had a plastic alternator pulley fitted that gave misalignment problems - this has a plastic alternator pulley.
Will try another garage