Nigel, I have done something similar in the past and the bees stopped building queen cells, the queen kept laying and was still heading the colony the following spring. Good luck.
I've also lost a couple of queens with no evidence of a queen cell having existed.
Beekeeping friend has been out to at least one if not two swarms every day for past 2 weeks. Apparently a lot have been small in size with virgin queens and have been hanging in one location for several days before they were called to collect, one off a small twig and another on a fence rail had both built wild comb. Wouldn't normally expect this, makes us wonder why they're not finding a suitable home.