So the missus informs me that the bath won't empty, which is slightly odd as it was draining fine when I had a shower this morning. Further investigation revealed that the sink would only drain VERY slowly.
Poking chopsticks and the like down the plugholes did nothing except vomit back big black lumps of god-knows-what.
Off to B&Q and returned with a plunger type thing that "works brilliantly" - 2 minutes into using it I snapped the handle off
Back to B&Q - "it must have been faulty" - so they gave me another and I returned and went to work. 2 minutes later I snapped the end bit that goes over the plughole off
In frustration I just put the snapped, flush face against the plughole and pumped away. All sorts of evil looking gunk was flying out of the overflow (all over me) and then suddenly there was a big gurgle and the water started to drain
I then poured a load of concentrated lye down the plugholes and left them for an hour before flushing through with hot water.
Sorted