Pedals, pedals and more pedals.
I went over to service
@gavgav's bike (well, more of a checkover/adjust really as it's still quite new). The one thing that it really did need was the pedals stripping and regreasing as they were quite gritty.
On the way home, my left pedal sheared off, which was rather inconvenient.
I've had to buy a replacement set and since my knockabout bike and both my siblings bikes used the same pedals I was a bit concerned about them suffering the same problem so had to investigate.
The knockabout bike has gone back to an old set of pedals for the time being and the ones that came off have been stripped for inspection. I can't find any obvious fault, but not sure I trust them enough to refit as the bike tends to get some hard use.
My brother's pedals have been rebuilt using the good parts from a low mileage but externally damaged set, so they should be sorted. Looking at the spindles that came out, his would have been the next to fail.
My sister's bike will have to be checked at a later date.