Well, at least we were home at the time.  Friday morning we were procrastinating over breakfast & the newspaper when there was a crashing noise from downstairs followed by the sound of water rushing through the pipes.  We ran to the basement to see water gushing through one of the potlight fixtures in the basement bedroom, shortly thereafter joined by two of the others.  A few minutes later we had the mains turned off but an almighty mess on our hands.  And we spent the rest of the day arranging and supervising an emergency plumber effort, followed by much of the weekend drying out the carpets (via rented carpet cleaner and borrowed dehumidifier).  The bedroom now has some very unsightly holes in the ceiling, and the pipes leading to the back bathroom now have shutoff valves (which are shut off).

Seems the renovator who created that back bathroom forgot about insulation for a portion of the wall.  The pipes were separated from the outside brick by about 3 inches of open air.

Obviously we’d have to call this a minor disaster, but at the same time we were immediately conscious of how lucky we were.  Half an hour later, or if we’d been more prompt in leaving for work, and that water would have been gushing for the entire day.  *shudder*