Hi again , This is a picture of the standard switch on the landing.
Red in Com , Red in L1 and 2 Black in L2
Below is a picture of the back of the dimmer downtairs. As you look at it , its the right hand side that operates the Landing light (The left side does the Lounge light and is working fine)
The right side is wired from left to right Comm Red , L2 Black L1 Black.
This is as it was wired before.
To go through the problem .. This all worked fine for 3 years (except that you had to have both the downstairs switch (the Landing light side) AND the upstairs switch , BOTH switched on for the Landing light to work. THEN , a few weeks ago , my son switched the upstairs switch , heard a 'pop' and assumed the landing bulb had blown . It hadnt, replaced bulb , still no joy. Local lad (no qualificaions) looked at all 3 items (ie both switches and Light)and could find no evidence of carbon etc. He however concluded that the downstairs switch was at fault. (Dont know why). So .. Replaced downstairs switch and whilst off the wall initially, it seemed to work OK (but as before ref both switches had to be on for Landing light to work) but i hadn't connected L1 Black securely. Thereby blew the main fuse when I screwed it back on the wall ! Connected the wire securely and switched on again .(NB havent used the 'dimmer' facility .. Just plain on/off) and this time heard a 'pop' and right hand side of the switch (ie the landing side ) again doesn't work . Lounge side still OK.
I really hope you can help because folks who dont know what the problem is, but continually try to give me advice are starting to get on my nerves !! Many Thanks