W124 320CE UK car (RHD) 151k miles

I have just changed a front left tyre (passenger side here in the UK), as the outside third was worn - never had that before so I'm thinking... something must be worn here. Also noticed the steering does not self-centre as it used to, I seem to turn the wheel back more myself these days. The other front tyre seems to be wearing normally.

All shocks and ARB bushes changed not too long ago.

Any ideas as to what could need attention?