sandydog wrote:
Hello

Can anyone help me wire a light switch in my loft? We've been without
light in there for about 6 years! It's our bedroom.

The thing is, there are three cables.

Cable 1 has 2 x red wires, and 1 earth
Cable 2 has 1 red, 1 black and 1 earth
Cable 3 has 1 red, 1 black and 1 earth

All three earths are joined together, as are cable 2 and 3's black
wires.

The switch was working fine until we had to pull the loft walls down,
and unfortunately we didn't make a note of what came from where. I
can't even remember if it's a two way switch working the landing light.
(The landing switch is a two way, one working the loft light).

Please, can anyone help me??

Any idea which of these wires goes to the light fitting? Get a
electrical screwdriver (one that lights up on mains) and carefully
check which of the reds are live. I suspect cable 1 is the switch cable
and cable 2 or 3 will be power and the other the light feed.. If thats
the case then cable 1 would connect to the two red wires together when
switched. However I could be wrong so perhaps better to get a qualified
electrician in.