I've been fixing and fiddling!
I have at last fitted the spare wheel carrier - it seems to foul with the penultimate exhaust box a tad. Anyway, it's fitted and whilst I was underneath I treated a load of rust and gave it a coat of body seal.
Upon investigating the apparent wheel bearing failure, I noticed a failed track rod end and that the steering was toeing out (inner shoulder of tyres wearing). I replaced the TRE and tried to - retrack it to prevent the toe out. From a rough measurement and the odd calculation I worked out that as a good estimate for the home mechanic, one full rotation of the TRE is equivalent to a 3 degree change in tracking. I found with the Xantia that when tracked at a garage for 0 degrees, the outer would always wear prematurely. Recommendation for Xantia and XM is 0 deg to 3 deg to out. So, I wound the TRE out 1/2 a turn. The difference is quite something. The steering feels lighter, the car seems more keen to go creeping forward on tickover, and the bearing noise, whilst still there, is much quieter (assuming it was/is bearing noise. Nothing is rubbing anywhere - but there is still a noise

)
One thing I noticed was that the o/s wheel was much easier to rotate by hand than the n/s - even with the pads out. Why would this be?
I have also done a full all round brake caliper bleed and again, not only are the brakes improved, but the rear end deosn't rise up when braking - it feels a lot more stable in braking.
I also made a repair to the drivers door seal - which was creating loads of wind niose. Need a test drive to see if it's any better.
If she carries on like this I'll have to treat her to a dot matrix repair!