Converting back to 2 way

[Wansbrough]

I have just moved into another property and wish to change the light switching in the living back to a 2 way configuration.
The previous occupant obviously wanted a dimmer switch and bought a one way switch, I have bought a 2 way switch so that the dimmer can still work. However, after opening up the boxes I am confused as to which wire originally went where.

At the moment, I have a one gang/one way dimmer switch which is wired like this.
Yellow (red taped) - connected to unmarked terminal
2 reds connected to other unmarked terminal.
Black + Blue (both red taped) connected together to a independent terminal block.

The other end is as this
Yellow connected to L2 terminal
Blue (red taped) connected to common terminal
The L1 terminal is empty
There is a red cable (red taped) going into a terminal block.

Any help greatly appreciated.

 

[Adam_151]

Yellow to common
Red pair to L1 or L2
Blue and Black pair to L1 or L2

Same the other end, except minus the black and the second red

 

[Wansbrough]

Jobs a good un!!!!
Many thanks for your prompt reply.