Late post, but just seen this...
Queen hadnt read the book and tried to swarm again 5 days later having laid up about 40 cells ....
LOL I think she had read the book! Once queen rearing starts, it's a swine to stop. Don't forget that she has been starved ready for flight, so you also interupt egg laying even if you do prevent the swarming.
Snelgrove boards are quite cool and can be used in several scenarios, but ideally there should be NO queen cells when you start, it works a little like false swarming. But much less space and heavy lifting is required. Flipping a few gates is hardly hard work! Don't forget your notepad!
Basically you leave your queen with very little brood and the flying bees, much like a swarm. The rest of the brood & nurse bees end up upstairs, where they create emergency queen cells (which rarely swarm). The idea of rotating the doors is to ensure that the colony downstairs has the maximum number of flying bees (imagine a swarm where all of the brood in the old hive follow the swarm as and when they emerge). It also starves a would be swarm upstairs of flying bees.
Once you have a laying queen upstairs (don’t flip the doors after Day 13?(forgot!
), otherwise you may loose your new queen into the hive below when she mates) you can now do 3 things. 1) Remove upstairs as the basis of a new colony. 2) Use the queen to replace 'her downstairs'. 3) Keep siphoning off her flying bees to create a powerful colony downstairs, until you get bored with flipping gates. 4) merge with/re-queen another colony. Then, when you're bored maybe option 1 or 4 (leave enough time so they will be able to build up for winter).
BTW, Varroa may become a problem.
Snelgrove boards are easy to make and well worth a play