Lurch wrote:
(Rob Gilchrist) said:

Am I right in assuming one of the cables is the main circuit and the
other is the cable to the light switch?

Chances are that one of the cables was the 'mains loop in' from the
CU
and the other was the 'mains loop out' to the rest of the lights in
the house. If it is then there should have been a third wire going to
the switch. Was there a switch in the lean to?

Hmm, almost as worrying as when the double glazing fitters plugged
their 110V transformer into my (seldom used) double socket in the hall
a couple of days ago.

'trip' went the 6A MCB on the lighting circuit :-0000

Time for a little urgent detective work I think ...

P.