I have a wall light in my sun long
E which is operated by a two way switch system. I have now installed a ceiling light and have lead a twin and earth cable back to the one of the switches. I would like to replace the single switch with a double dimmer switch to operate the wall and ceiling lights independently. The existing switch has wires to COM, L1 and L2 what are my connections please for the new double switch.
Uk wiring regulations apply.

Please reread what you typed and make corrections. It is most likely not going to work since you would need and extra black/hot wire going to the fan. You currently only have one hot wire going to the light, correct?

Basically you would need to rig a jumper from the switch connections at the existing light and run those connections to the new light.

I'm not privy to the wiring standards in the UK as I have never studied them.