As promised, here are some photos of the Koi and other fish, all grateful to have their filtration plant back up and running. I do have a backup pump in the garage, just in case, but it's not as powerful as their usual one.
The largest of the fish are about 12" long (Fisherman's 12") and were all bought at about 2"-3".
The two fish to the left of the first photo (9 o'clock and 7 o'clock) are fish which were bought for me as a birthday present by a colleague and her husband four years ago. They were less than 2" long when bought and are now 7"-8".