Light fitting changing help

[SamHolmes2021]

I'm just swapping out some old switches and I'm trying to understand the wiring and how to wire in the new switch.

It's a double 2 way switch, so one controls a light downstairs and the other controls one upstairs. The upstairs light has its own single switch upstairs aswell

Thanks for any help. I've tried reading other threads but still struggling to understand the correct way of wiring it in

 

[EFLImpudence]

Well, this will be the usual way going by the wires present but -

I am a bit puzzled by the markings on the old switch.