To get back to my point......there was no sign of Queen cells. This is more a case of a newly mated queen getting into an established built up nuc (she must have drifted? Maybe I should re-site my nucs round the corner?), that had a fat laying Buckfast bought from a very respected supplier, UK. Nothing wrong with the queen for 3-4 weeks then hey presto new one has taken up residence! I thought this was not supposed to happen! Surely the bees should have refused entry? I feel that new fat bee queen has killed established Buckfast.