Warm!

Central heating restored, so I can actually use my living room for the first time since I got back. (It's a bit too large to successfully heat with a fan heater). The engineer just squeezed into his 10 'til 2 window, but was done in about an hour and a half.

I was surprised that the problem was a failed receiver for the wireless controller, rather than something mechanical, though the system had also managed to depressurize itself. So even though the controller was constantly saying "turn on, it's cold", the actual boiler was sitting happily idle. And of course there's no way to control it manually - slight design flaw, methinks.