Bolstered by a cup of coffee, I thought it was better to attack the single slip before I chickened out. Inspecting Man was less than impressed:

I should point out the rationale for doing this - the single slip really doesn't make much sense for the layout as it is, and if I'm going to be operating it on my own for a two day show I think it's worth some pain and delay now to make the operation as simple and sensible as possible. With a double slip, I can bring trains in on the correct line, and then work them into the yard with a single movement as opposed to a shuffle. It'll also be possible to bring longer trains in and it'll avoid clogging up the depot and loop to boot.

So... having bought the slip, does it fit? I know it's supposed to, but nothing beats checking. Plus this bit was easy

Next step was to disconnect the feeds to the stock rails and frogs, and remove the point motors so there wouldn't be any stress on the operating arms. Then I removed the paint from the rail joiners, and was pleased to see I hadn't soldered the joints because all the rails are powered by wires anyway. I cut through the rail joiners with a Xuron cutter for the meta ones, and a knife for the rest. Naturally this was after a couple of abortive attempts to open them out with a screwdriver Cutting them makes a lot of sense - it's easy to pull the remaining half off the rails that remain in situ, and there's no force applied to the rails.

With all that done I went from one end to the other gently levering at the sleeper base with a small screwdriver.

...and with a bit of fiddling the feed wires through the holes, out it came. The surrounding trackwork is almost unscathed, but I did lift the rail from a couple of chairs at the lower left - odds of getting it back in are low, but I can trim half the chair away on the side away from the viewer so the rail sits flat, and trust the double slip to set the gauge, possibly with the aid of a drop of superglue.

Cleaned up, the damage doesn't look so bad. I need to make some modifications and solder feeds to the double slip, spray it brown, and install it.

Just hope I'm not chasing poor running gremlins for the rest of my life - the trains ran through the single slip very nicely indeed