You know what they say - need a job doing properly, call an expert.
I tried to wire a ceiling light on a loop on Sunday morning and the result was no lights at all until monday morning. Paul turned up at 9am monday and within 30 minutes had everything working properly. Ceiling light wired correctly and also fixed a faulty wall light while he was here.
I should have called Wiring Works in the first place! Lesson learned. Thanks Wiring Works.