Dimmer wire connection tightened (yellow arrow).
Moment of truth........it works!
Remarkably, reinstalling everything was much easier than the disassembly. The connectors just went click, click, click as opposed to fumbling around with locking tabs and lacking sufficient hand manoeuvring room. Having done it once now, doing it again would be much quicker.
I think I’ve been let off easy this time. Phew!! Good night all.