I have recently bought a cup, there was no receipt for the cambelt, only a stamp in the book with "cambelt changed" written underneath. It was done by a local garage who are out of business now, so I couldn't ring up and check.
I took it to Fred in Birmingham yesterday for a cambelt and Dephaser change. Turns out the local garage had got the timing out, and had hammered in the locking tool to make it fit, damaging the end of the camshaft in the process. As well as using the wrong spark plugs.
Long story short, see if there is a stamp in the logbook and ring up and check it has been done properly. If not, try and knock off about £450 as that's how much the service would be (£300 without the dephaser.)
On a side note, I would definitely recommend Fred@BTM for anything cambelt related.