Many thanks for the reply. Will have to wait till the morning when the light returns to take a look, so will update the thread then.
If there's no update, please send an ambulance :)
Very frustrated.
Finally got round to replacing the ceiling light in the living room. Wired it up, turned the mains on again and, let there be light. Sure enough there was plenty of light, however, when I flicked the light switch to turn them off, they refused to comply and stayed on.
Checked...