Well, positively racing ahead - only 3 weeks since my last post.
The threatened bout of track-laying has come to pass, and things are looking as if I might have meant them to be that way. As always, modifications have been made as I've gone along - particularly in the fixings of the end sections of the 'track round the back':

The spring clips weren't quite positive enough in holding the ends in place, so roller catches have been fitted in their place. This is the mine entrance end, and the track extensions for the faux-point have also been installed to complete the illusion (hopefully).

This is the other end - visible at the bottom of the end section are pieces of card needed to fine-tune the height - my woodworking is even rougher than I thought!

A close-up of the fixings at the rear of the end sections. The position of the roller catch near the middle of the section left some 'float' at the rear, so this agricultural latch has been added. With the 'horns' at the front and rear the whole thing is now rigidly fixed together.
Electrical continuity is by means of springy brass wire 'horns' soldered to the ends of the rails on the end sections, which make contact with the ends of the rails on the front and rear sections when it's put together. This worked well on Wood Bros, but might need some tweeking to get good contact on all 8 connections. It also helps with fine rail alignment.

A look along the rear of the layout, showing how it comes together. The 'bridge' for the controller also had some modification along the way. Now the track has been laid on the end sections hardboard end facings will be fitted to hide the 'orrible goings-on.
Next task is test-running over the circuit and some cosmetic treatment for the bit of the mine interior that will be visible from the front.