Hi again, thank you for your reply, I understand now the wiring names, live, earth & blue being the neutral. In my fuse box there is a switch to turn off the power to the upstairs lights ( 2 bedrooms, 1 bathroom & the landing light), so presumably they are on the same circuit. My bathroom light also does not work, we had arranged for him to replace the existing broXXXXX XXXXXght with a new one I had bought, but he said that it was not suitable for a bathroom ( I did check this as it was sold to me as a bathroom light & the area that the light is in as far as I can see is a zone 2, which the light is meant to be suitable for, I did buy it from a reputable company). Anyway, could that be the problem? I'm not sure that he did anything with the bathroom light as he thought the fitting was incorrect.
My previous landing light was controlled by a normal on off toggle switch on the wall. I'm sorry but I didn't understand the map of the circuits you attached! but when he mentioned the junction box, which is probably in the inaccessible void, would that be where there might be the loose wire? if it is therein lies the problem, but if I understand you correctly
it probably isn't? I realise it isn't easy to know but are there things he could do to check the probability before he cuts the ceiling, I don't really want to be fobbed off by him & overcharged for work that is not necessary. You have already been very helpful, but I just need to check that I have grasped your answer correctly. Thanks.