As I've done all the track wiring, I can complete the base board construction I pin more 3.6mm ply to the underside.

Its another 6' long piece but split into three pieces, two short ones at each end and then third one turned 90 degrees to give me a small shelf to fit the controllers on. It just fits the three controllers (two power, one for turntable). Small holes in the shelf allow me to feed the power-cables to the controllers from beneath.

At this point I'm running FS and a garter-blue Union of South Africa. As my wife hailed from that vicinity she had a strong affection for blue trains, and having one named UoSA quickly put it on the top of the list. It's possible I've got multiple models of UoSA in three gauges...

Wiring for the turntable:

The Kato turntable comes with its own controller that gives you control over the direction of the table as it turns (as you would expect) and perfectly stops only when rails are aligned. It also routes power to the table rails and has a back-off-forwards switch to control the polarity. You get some insulating unitrack connectors with it, so that you can arrange the wiring however you want; I went for the simple way of isolating the track that leads to the rest of the layout after 6".

I then feed both the inner circuit and the turntable from the same power controller. This means I have to ensure I've matched polarity between the turntable and the rest of the layout to actually run a train off it successfully. Because I know its easy to get confused I've added a pairs of LEDs, one pair fed from the turntable and one from the main circuit, if they both light up the same colour then I've matched polarity, if not I need to swap the polarity of the turntable. I'm sure after operating this for a couple of years I won't need to look at the LEDs, but then with the march of time I just might need to look at them more often.