Coilovers fitted (bottom). I'm not happy with the rears, they are on their lowest setting and look like I'm about to tackle the Monte Carlo Rally. Better (
maybe) than how they were before, which looked like I'd got a body stashed in the boot (top). The front still has some adjustment available (although I ran out of effort in the heat yesterday), and also it seems pointless to spend time tweaking them while I am in discussion with the seller about what can be done with the rears in case their only solution is to return them. Alternatively I might just delete the adjustment mechanism and see how it looks.
(If you're wondering what is going on with the top spring pad, I had to cut the 'cap' part off so that the top ring of the coilover would fit over it. I thought that leaving a millimeter of the flange would help keep it centered, however I suspect that the spring pushing into that tiny lip has slightly stretched the rubber/silicone and caused the outer edge to bow inwards. Depending on what happens with the coilovers I'll probably replace the pads)
I also think I found the source of the knocking, on the driver's side, the two T40 bolts holding the rear subframe bracket to the chassis were not very tight. I loosened them a few weeks ago when I was going to try and change the main beam bushes on the car. I'm not entirely sure whether I forgot to torque them back up, or if they have worked loose, however they're tight again now and I shall be keeping an eye on them! I'm going to do the rear subframe refurb this autumn/winter anyway, so I'd rather they be too loose than too tight!