Unusual 2 way switching.

[HaywardI]

Seems very complicated just for a loft light. Can't you tuck a neon indication in a wardrobe or cupboard upstairs so it's not on show.
If you wired from the loft light switch, through a a switched fused spur (with neon) then onto your loft light, you then have the option to isolate the loft light from the switched fused spur if you found you accidentally left the loft light on.

I'd think I'd rather that then someone turn off the landing light while I'm trying to work in the loft.

AJshep, It looks like I may have to do just this. I have found a cheap 240v 5a LED (£3ish from my local trade store).

My problem was not that someone turning off the landing lights would turn off the loft lights, it was that linking the loft and landing SW L connections works in both directions. Therefore whilst I could get the landing light to come on when the loft light was on, it also works the other way around, when the landing lights are on, the loft light is also on and I don't want that behavior either.

I did consider using a high voltage diode, but that would only allow + current flow so I would get some very odd behavior from the landing lights (probably flashing 52 times a second), but this would be a hack at best and I am not skilled enough in electronics to build full wave.

Take care and thanks for your help!