Yes, I turned the radio up louder. But before I did that, I had the wheels off and couldn't find anything that accounted for the noise. The back plate on one of the rear wheels had cracked and I removed it but that made no difference. Apart from the knocking, other issues started developing, such as, the rear window would sometimes open of its own accord, often in the middle of the night whilst parked. Then some days the rear door would refuse to open. There was a miriad of not serious but annoying faults and it was coming to the end of its mot so I sold it cheap to someone who was willing to deal with it. It was a great car though and I enjoyed driving it even though it was the underpowered 1.8 Now I don't work anymore, we don't need three cars so it had to go, I've still got my beloved series though.
Col