£120 including plasterboard, where are you 1970?
I would have chased him.
I'm not sure what you are getting at.
It may have been higher, but under £200, and only 3-4 years ago. Obviously cash-in-hand.
It was done in two goes as I could not live long enough without a kitchen and having to move the electrics and gas. The second bash was 3 walls, with two large windows and two doors, so lots of faff - the guys who did it called in after normal work, on their way home - it took no time at all and it was well under £100.
Before you ask, one neighbour and one friend had some plastering done around the same time, and the work here is way better than either of their jobs - blemish-free so far as I can see (and I have painted it, long ago, so got up close).
This looks like 3 long, but not rushed, days' work, so, £30/hour(???), that gives around £800, plus materials. The only tricky bit might be connecting to the cast pipe, otherwise simple enough. But then I don't have to make a living at it.