Coming home from Doncaster show yesterday with 4 people in the car i noticed a knocking noise from the rear of the car when coming to a halt. The noise almost sounds like something catching but happens about 3 times per wheel revolution. It only happens when coming to a stop at very low speeds and it stopped when my rear passengers got out.
Anyone have any idea what this may be???
Car is an MY99 turbo with P1 wheels.

Have you put after market shocks or springs in the car? If you have this is a common problem with the rear top hats. What they do is replace the top hat bushes with say nolathane bushes or replace the top hats.