I'm trying to replace an old 2-gang switch (operates 2 independent lights) with a new dimmer switch. Got meself in a bit of a tangle! Having removed it I can't remember now how the old switch was wired (so no lights in the room for Christmas - dumb or what?). There are two sets of red and black wires plus an earth-wire to the switch backplate. The new dimmer switch has 2 sets of connector blocks with an L1, L2 and Common on each. I think (slight exaggeration my wife says!) that one red and black pair went to an L1 and L2 terminal, while the other pair went to a Common and either L1 or L2 terminal originally. Unfortunately, I can't recall which wire went to which terminal though (although I know which red and black pair are which). I'd be very grateful for any advice on how to wire this up. Thanks