Aye Tobz, cambelt tensioner. I had a fanbelt squeal on my old cab and it turned out to be the cambelt tensioner so I had it replaced. The bad news/good new is that the garage for safety reasons also changed the cambelt to be on the safe side.
Got an idea, take the fanbelt off and start your car up, if it still squeals it will more than likely be your cambelt tensioner, that's how I confirmed my problem.
P.S. I did try WD40 but it didn't make a difference.