Deed done this morning and all went smoothly - she walked happily into the trailer after her bucket of nuts, bedded herself down on the hay and travelled well. The vet underestimated the size of injection needed, so I have a lovely final memory of her flat out in the trailer, snoring loudly while I scratched her behind the ears, as he refilled the syringe.
Vet and incineration people both said no paperwork needed, the incineration people would report her tag number themselves, so I just needed to record it on ScotEID and in my flock book as a death. Vet and lab staff both lovely to the middle-aged woman attempting to hold it together and not quite managing, though I did manage to hold off from the proper snotty-nosed blubbing until I was back in the truck and had driven away! Seeing how stiff she was getting up first thing this morning though, I know I've done the right thing, and 13 is a pretty good age for a hill ewe.