Re:
I did eventually buy the Diamond Back Ascent EX discussed above, on July 26th this year.
It arrived at the courier depot today, 4 months after paying for it (that's how long it took the seller to get the pedals off). :facepalm:
Here it is just out of the box and hosed down. The wheels look like the originals, the Mountain LX drivetrain is intact, and the DB handlebar polishes up OK. The only downsides are both shifters are bust, the headset has gone south, and the seatpost is very rough (I can't see the size on the post, is it 26.8mm for this?).
I already have a replacement T-Bone stem and an Avenir saddle, and it's now rolling on Tioga Psycho and TT tyres. All it needs is dismantling, cleaning, greasing, tightening, and new cables.
Now bad for £38.00.