We checked the state of the hives, and added top boxes which are half the height of the main hive. Between the main body of the hive and the top box there's a grill, the spaces in the grill allow the worker bees to pass "upstairs" but not the queen, so the upper box is used only for storing food - honey - but should contain no eggs or larvae.
The ruchette needs to be sealed, then left in a dark room or garage for 24 hours. it then has to be taken at least 3km from the original hive before reopening the bee entrance. It's left in this temporary setting for 3 to 4 weeks, before it can be returned to the original site.
We have no way of knowing immediately whether we have moved the queen to the ruchette, or left her in the original hive. The theory is that the bees without a queen will feed one of the very recently hatched larvae extra royal jelly, in order to create a new queen. Apparently within a few hours you can tell the bees without a queen as they behave a bit odd, as though they start doing something then can't remember what or why, due to the drop of pheromones in their hive. However the confusion is only short lived.
Apparently there is a 90% chance of success if you do this with a healthy, full hive from mid April to mid August.
Trap now re-baited.