In message
ilgate.org, Clive
Dive wrote

Any ideas on what is causing this and what I need to check ?

TIA,
Mike.

Classic DIY error

SWITCH OFF AT MAINS

2 blacks to neutral. 3 reds on a separate connector [theses are; live in
, live out and live to the wall switch.] remaining red to the L
connector on the fitting.

That would require 5 lives
live in
live out
live supply to switch
live return from switch
live to lights

The OP said he only had 4.

As a guess this is a spur connection rather than the lights being on a
ring.

Trial and rror unless you have a tester
/ meter I'm afraid.

The OP is lucky that the wires to the switch were BOTH red!

--
Alan
news2005 {at} amac {dot} f2s {dot} com