Any question answered...

It's works for screw-on hubs, but is no better than a suicide hub; the lock ring is purely decorative, as back torque simply removes the adaptor from the hub instead. The axle might not fit a disc wheel hub, but it's pretty easy to rig up a track axle for pretty much anything, especially if that anything has cartridge bearings.

So the one I linked to, the fixed thread and lockring thread are one unit that just screws onto the freewheel thread? That sounds a bit crap for £80.

Typically about £40 for an axle and bearing retainers from your local machinist.

And would it be possible to find someone kindly to do that for me, and use their local machinist instead...?