Finally got it done today. Replaced the centre console with the black ash one complete with IWC clock. I cheated and got an auto electrician to do it as my DIY skills leave a lot to be desired
I bought the console with IWC analogue clock on eBay, the wiring harness was from Braybrooks. The harness comes with full instructions of where each wire goes and comes complete with the Mercedes plug which fits into the back of the clock. In archive threads it states that you have to put the yellow wire into the SAM module, you can actually put the yellow wire into the back of the switches directly above the headlight switch, in my case it was the parking sensor switch.