I did say my money was on the shock at 10:52 this morning. How was I to know you'd be up with the Lark!!Now he tells me!
I just spent over an hour taking the bush apart then another thirty minutes getting the new bush into the alloy cradle and it made no difference. Grrrr
To be honest I'm not surprised, the rear bush was in good condition (until I butchered it) so my money was on the strut. It is the only thing left unchanged on that corner.
Top tip. DON'T BUY A BARE BUSH! If you value your fingers, tools, time and sanity buy the bush and alloy cradle complete.
I still think it's the shock though. I had a similar knock on my ZS180 that I simply couldn't trace. Eventually I had to change shock because of a leaking seal. Once the job was done, it occurred to me that the knock had vanished!! So I set the old shock in the vise and yanked on the rod. There was the knock, although softer because I'm not as strong as the car!!. I decided to cut the shock open to see what was up with it. It turned out to be play between the piston and the rod. This play allowed the rod to move almost 5mm before the piston moved, making a knock when the rod contacted the piston.
Yes those bushes are a challenge to change. Cutting the old one out is the best way. Refitting requires a press or very a large vise, but a threaded rod and some spacers will also work, just.