The clue is in the name - he is in Craigavon, County Armagh. Local knowledge helps.
The swarm may not have been queenless at the start.... I have helped gather up a couple of small swarms/casts for people recently and spotted queens as they were being rehomed. Two+ weeks later, no queens. Test frames confirm Q- status. My thinking is that the queens didn't make it home from mating flights. In both instances, the bees began drawing comb and then appear to have stopped. I have encountered Q- nucs and apideas drawing comb in the past also.