A sensible comment.
Are you being serious? I think he had got to this point.
And so do you. His logic was perfect. Why say this?
One downlight flickered, they all then dimmed down and briefly came back on before going out again and none came back since.
MCB.
Thanks for confirming my sanity... Thought everything was fine with that parallel statement and installation.
So a general update...
Did some proper testing as best I could.
General short summary in my terms is that something live is touching something neutral or vice versa.
My reasoning for saying the above is that if you open up a ceiling rose (I checked two at different ends of the house)... With an old style tester screwdriver (with the little light in) everything lights up the screwdriver! Neutral, live and switched live all light the screwdriver. Checking it with the multimeter just shows something minute like 0.8v. I assume this is because there is no real complete circuit despite every wire being "hot".
With regards to the MCB... It does trip when turned on... But NOT instantly. Takes between 8 and 10 minutes roughly which I find strange. I thought it was related to turning on the bathroom downlights but that's not the case as it has also happened with them off, and also with other lights turned on. Bit difficult to check if the landing light is on because it has 4 switches that can control it.
So the general consensus is that it seems to trip after a few minutes, regardless of light switch positions.
There is a junction box at the two bathroom downlight setups (one each) and I also disconnected the string of 6 lights (the potentially questionable ones that flickered) from their junction box (leaving only the pull string switch and extractor fan connected). I thought this solved it as it then didn't blow but it didn't solve the problem since no other lights began to work either. Also I then touched the meter to the junction box and around the same time it tripped (could have just been a badly timed convenience).
Also checked my ceiling fan light connections as I read about that being a potential cause online. I hadn't used the fan for months until the morning of the flickering. But all connections here are solid.
Thoughts are appreciated on the above (all wires being "hot" situation)... But at this stage I'm running out of ideas and will possibly just end up waiting for an electrician on Monday (or the same guy who came today on Wednesday when he's free)
Good to note the electrician also noticed something strange in the same rose I was checking out... Dad didn't quite catch his explanation of it though but I imagine it may have been the fact that all wires seemed hot.
Thanks all
Feel free to throw any ideas out there! Will be much appreciated