Update: having fitted a new stylus, re-balanced my tone arm and listened to the first half of side 1 of the LP with no problems, I played the rest of the album... and found it mostly unplayable.

The vinyl looks fine: no surface dirt, no scratches or other marks. But there are a lot of loud clicks and other noise - for several entire tracks it sounds like someone was frying chips in front of the microphone - and in many places the needle skips. I guess it just is a duff pressing.

One odd thing is that in some (although not all) cases the noise subsided if I played the track a second time. This made me wonder about static. The turntable has an earth wire, but it's currently only connected to my audio interface, which doesn't really take it to the ground... if that matters? (IANAElectrician)

Overall it looks like I've laid out on new kit to prove I didn't need it! A new stylus and a pressure gauge aren't a bad investment, though.