ss wrote:

The 5 amp socket I intend to use does have shuttering. Another quesion:
Does it matter that the light switch is also a dimmer switch (re 20watt
outdoor floodlight LED with PIR)

It doesn't matter to the plug, socket or wiring, but unless the LED says
it's dimmable it won't run off a dimmer switch, even then you are likely
to need an LED specific dimmer, the load will be too low for most
"normal" dimmer switches.

But I doubt there are many outdoor floodlights that *are* dimmable ...