Just to add to SMD's comments....
The belt had also been over tensioned. This has had the following knock on effect:
1) The outside run of the belt had been basically "melting" itself to the idler faces. You can see by looking at the belt and the idlers that this is the case.
2) It's put additional strain on the bearings etc in the idler pullies - they didn't feel like pulleys that had done 5k when rotated.
Also, as mentioned, the belt had been rubbing a little on the inside edge.
The only reason I could see for this is because the bolt securing the lower idler was practically finger tight. I wonder if this has allowed a little movement, and as such, caused the belt to rub on the outer lip of an idler.
We could guess all day, but my instinct is that this belt kit was not fitted using the proper setting tools (merely cam locks)
In all honestly, although this cambelt kit has only done 5,000 miles, I don't think it's got another 35,000 safely left in it, now.
If the car were mine, I'd replace it, along with that awful howling pattern waterpump. If you want to get the parts and bring it down / meet up sometime, we can do the honours...