I had my anti roll bar changed for the second time in about 40k miles as there were knocks and movement in the bar.
About 2 weeks later the knocking returned and upon inspection the bolts holding the d bushes had worked loose.
The bolts appear to have had copperslip applied to the threads, which I can only assume is why they worked loose.
I have nipped them up tight again and if they work loose again, I'm going to clean the copperslip off and put some thread lock on.
I wonder how many bar bushes have failed prematurely due to loose bolts,I suspect lots!