Hi, I appreciate that this might be hard to diagnose remotely but I'm at a loss of where to turn next.

Here is what I know;
My car is a '65 Deluxe. I've recently had the car at the trimmers for new carpets. Prior to that the lights were working fine, but I couldn't tell if they were working immediately after coming back from there.
1. My headlights aren't working, but the parkers do.
2. When I switch the lights on full the L.H rear indicator globe is illuminated, but no main lights. With the parkers on, the LH rear indicator isn't illuminated.
3. When I turn the indicators on for the LHS with no lights on, the indicators work. With the parkers on, they flash but only on one filament. With the lights on full, the LH indicators dont work at all. With the LH indicator on, the high beam globe in the speedo flashes.
4. I've checked the headlight globes and they work. I've checked the front parker globes and they're okay.

I'm sure there is a simple answer to all of this, but I'm really not sure which way to turn or where I should be focussing my efforts.

Cheers,
James.

Like you said it is not easy to diagnose a fault like this remotely especially when one does not know what has been done to the car.
It sounds very much like you have an earth missing. But also Dip switch might be at fault too.
(1) Check the earth wire behind the speedo. (Black)
(2) Check the earth wires on the front of the Bulkhead Driver's side, remove paint from under lug and tighten bolt.
(3) Check also the one in the boot close to the Fuel tank strap bolt. Remove paint from under lug and tighten screw
If they are OK then check the Black wires in the bullet connectors for the front lights behind the grille.

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
"Let us remove your "SHORTS"

What about the dip switch? Wires not reconnected?

Ok If dip switch wires are not connected why do indicators light up when not asked to?

_________________
DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
"Let us remove your "SHORTS"

I have found over the years trailer lights can play these sort of tricks when the chassis forms a common earth/grounding.
I am with David & would check the floor dipswitch connections seeing the trimmers have been poking around.

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.