I got out to see if the engine could still be turned over using the starter crank handle, but no, the engine wouldn't move. Something had broken. No amount of rocking the vehicle while in gear would free the flywheel.
Given that when trying the ignition button again, there was absolutely no noise from the starter itself, but the lights on the instrument panel went dim, it seemed likely that the starter had jammed the flywheel somehow. Either that, or something major had broken inside the engine. As the starter would likely need to come off in any case if the engine needed major repairs, removing the starter to see what was potentially wrong there seemed the logical first thing to do.
As the steering linkages were in the way, I elected to take the wing off, followed by the forward exhaust pipe and the exhaust heat shield. That way I could see clearly, too. Only difficulty was the -10 C temp in the garage. Even the shop hand cleaning lotion had frozen. (I have to say those front mudguards do a great job at stopping dirt etc., from accumulating on the bulkhead.)
With everything off, the starter was easy to remove. As it came out, it was plain that the spring, pinion, etc., were just floating on the shaft and everything slid off as the starter came out. Clearly the nut on the end of the shaft had come off. No visible damage to the flywheel, however, which was good to see. The engine turns over by hand as smoothly as ever.
In the photo below, the hole where the starter was. At the very back, it's possible to see where the spring, or something, on the shaft had contacted the bell housing, making a few gouges before everything jammed.
I managed to get everything out except the nut itself. A flexible magnet should take care of that. Below, the remains of the nut's threads still on the shaft. Shaft threads appear to be in pretty good shape. Split pin that held the nut in place was neatly cut each side where it comes out of the shaft.
The starter out. As I'm not sure what kind of damage may have been done to the shaft or the internals of the starter, I have ordered a re-built unit from 3 Brothers Classic Rovers.
While I was back there, I had a good look at the original block heater. It hasn't been tested. Cord just plugs in like any other appliance, although the rubber cover on the cord side had melted somewhat. I don't know why.
A slightly blurry view of the cord's socket.
