Managed to make some progress today. The MoT it had come with had condemned the front left flexi-hose, so I took a look:-

The hose was indeed in poor condition, but so was the pad fitting, the bottom pin was missing, and the wire clip had been looped around (because there was nothing for it to slot in at the bottom) and was in danger of falling out and getting stuck between the pad and disk! These brakes were indeed in a dangerous condition!
So a service was needed:-

I replaced the flexi hose, and a used new pad fitting kit to sort out the pads; I hope these bits are in the right place (please let me know if not!).
Also did the usual slider free-ing off at the same time (the bottom one was seized, top one was ok).
Still have the n/s CV boot to do ....