Trying it on a few hives so thought I'd start a thread on it.
Thought that keeping the hives big and no excluder was supposed to prevent swarming but went to a yard today and found this. Had seconds, literally, to stop them leaving. It's spring here the flow has not started yet. Or at least, there has been a willow flow at this site which has finished, there is now a tiny trickle although the bees are barely pulling foundation, waiting for the main flow.