I came home and rang the emergency council repair number at about 7.30. A man got here for 10ish. He went upstairs and came back and told me he hadn't found anything and thought it might be the fact that the guy upstairs has a wet room shower and the seal could have gone. He said he'd get in touch with the repair man to come out on Monday and reseal it. I said that he wasn't wet at 7am when I knocked him up out of bed so I didn't think the shower was the problem! He said to ring him if it got any worse.
I kept checking and at about 11.15 it started dripping quite fact through a crack in the ceiling so called them again. He got here about 3pm and agreed that it was worse so went back upstairs. There was lots of banging and clattering and he came back and said he'd found the leak he'd boxed in his pipes and then tiled the boxing in the bathroom so the leak wasn't showing.
Anyway it's stopped now thank goodness without too much damage and It's drying out nicely. I may need to just do a touch up paint job on the wall.