This was most displeasing, and much profanity was expressed at the time; especially as I was 200 miles from home.
Fast forward 15 months, and the car is still in my possession; and it's time I liberated my drive-way. In all honesty; I've done nothing with it, since getting it back home, on 18th November 2013.
The car only has 1st and top gear; no 2nd, 3rd, or reverse. It was driveable; by revving it close to the redline in first, whereupon it would clunk into top. Once in top; you had to maintain the revs between 2000 and 2100rpm; above and below that range; drive would be lost. I did have the transmission drained of ATF; to see if there was any swarf or debris; but nothing was visible. The ATF was replaced.
Other faults; from memory : The plastic hook for the boot-catch is broken, so the tailgate is not secured. The plastic trim inside the tailgate is missing. The roof aerial is broken, at the base. The interior light, and sunroof motor is removed. The glove-box is missing a hinge pin (I did fix this fault, once).
Things that DO work (or at least did, last time I checked) : The segment-display for the gears works (I fixed it). New (mid-July 2012) full exhaust, from manifold back. New (21-04-2012) Bosch S5008 battery (780 cranking amps, 77AH, 5 year warranty). I also replaced the alternator/battery cables, as the originals were a little corroded, causing high-resistance. I rebuilt (with much help from Jim on here) the injection pump, so that had all new seals. The front spheres (top of struts) were replaced. Didn't get round to replacing the rear spheres, but still have them. Oh, and I replaced the front and rear wiper blades (with Bosch)

At the time, I did consider having the transmission replaced. I was offered a recon box from a member on here, for £150, and my garage quoted £300 to do the box-swap. I was advised to have the torque-converter reconditioned, which would have been another £125 to £150. So I was looking at £600, and decided that was too much. I'm now driving a 2002 Volvo V70 D5 SE; and have to say it's been a lot less troublesome

If somebody on here, has the time and expertise, then this XM can live on. The engine never gave any trouble, and I've just remembered I did a cam-belt and water-pump change, back in March 2011.
Obviously; as it has been parked up; it is without MOT and VED; so can't be driven away.
It's too good to be weighed-in, and cop for the £125. So I either sell it as is, as spares/repairs; or I may break, if enough interest. If someone wishes to come down with a good transmission, and do a box-swap on my driveway, over a weekend; then that may be possible; though I can't provide accommodation. I can, however, provide an engine crane.
Offers / thoughts / suggestions welcome
Justin