Except when I actually pulled the super out, I realised I had put the bee escapes either side of the old brood super on top. The result was that I had a super full of old brood, some very discombobulated drones, and no honey.
Meanwhile, the super immediately above the brood boxes was, sure enough, packed with honey and also packed with bees.
"Oh f-f-fiddlesticks," I said to the bees, and "b-b-bother."
I re-ordered the supers into the correct positions, and will come back all over again to re-insert the escapes and have another go.
Incidentally, the bee escapes are not much cop. In both of them one of the two exits was blocked by a dead worker, and the drones are too big to get out at all. Health & Safety may have to be informed - I mean, what happens if there is a fire?
Pic from http://www.viking-direct.co.uk/, of course.