The top corner of my back bumper has a few dings on it where things have been dragged out of the boot. It's been inexpertly resprayed and looks a bit messy. I thought I'd be able to find a plate or strip (metal or plastic) which would fit on top of the bumper with a lip over the back edge to protect it, but I can't find such a thing - lots of metal versions of the plastic tread strip that's already there, but that doesn't go to the back edge.

Does anyone know of such a thing?

Only thing I've ever seen that protects that area are fold out flaps as part of a boot protector. Not what you're looking for I know, but thats the closest I've ever seen. Learned to drive in 2011.
Bought a Micra - great little car
"Upgraded" to Kia Sportage - hated it
Proper upgrade to FL2 TD4 GS 60 reg Facelift - tailgate paint issues, fuel gauge rewire, transfer box failure at 36k miles, clutch at 60k
Reconditioned diff at 70k ish
Sold at 84k and now on a DS. Terribly unreliable.
Sold DS for a 2021 Mitsubishi Outlander PHEV. Fingers crossed....
Sold Outlander for a 2014 SD4 SE Tech because I’m mental

you can get clear plastic film which is also used on the bonnet to protect from stone chips.. that may work but I guess would need periodically replacing if it gets damaged

I assume that you are looking for something that will cover the existing /poorly repaired damage. Something like this might be able to be cut and applied neatly to cover the damage perhaps? Ebay item no eBay Item No. 352922402396 or Ebay item no eBay Item No. 332842327332

Yes was trying to find something to cover up the slightly damaged bits. That rubber strip looks worth a try. Thanks