In case it's of interest to anyone else.

I've had a squeaking rear-end (ooer, missus ) when going over bumps, shutting the rear doors, etc. Traced it to two things last weekend.

1) The catch in the bottom of the boot (that the metal bit of the tailgate clicks into) was loose on its bolts. Tightened them up with a 12mm spanner

2) The wheelbrace (under the sheet of cardboard above the spare wheel) had shifted and was squeaking against (I guess) either the spare wheel rim or tyre. A bit of repositioning and all was sorted, except that it looks like my 'bit of cardboard' has warped

So if you've got a squeaky rear-end, try these two things before worrying about dampers, etc.