I think I've just found what this is - it's an intermediate switch that requires 2x in and out - I will need another intermediate to replace it.
Still begs the question what the cable is and what the brown is doing though.
I have a 2-way switch for a hallway light that has just broken (one of the plastic pivots as snapped and the entire assembly has popped out).
It has 2x L1 (grey wires) & 2x L2 (black wires) in the switch and brown wires connected with a choc block.
The replacement switch has L1/L2 and a COM...
Thanks all, it was installed whilst I was out (yesterday) so they were off site by the time I returned from home.
I'll get in touch and failing a response do it myself.
Thanks for the responses, much appreciated.
Where are these options? I only have Systems Sound Demo menu, nothing to change the volume/type of panel noise. The one that's currently there is deafening.