Can a queenless hive swarm out of congestion?

I've got a queenless 14 x12 that has swarmed and it shouldn't....

A brood chamber with queen and 5 frames of brood (standard 8.5" Nat frames) was united with a reasonably full queenless 14 x 12 several weeks ago. There are 2 supers, one quite full but uncapped, the other 1/2 full. One week ago there were queencells in the 14 x 12 so I removed the queen and 2 frames of brood and put her in a nuc. She is still there.

What was left in the hive was a lot of bees, 8 frames of brood of all ages in the 14 x 12 and a few remnants of sealed brood in the brood box under as the queen had moved up to lay in the 14 x 12 brood box only. Yesterday I cut out all the queencells by shaking all the frames and cutting out anything that looked like a queencell; leaving the hive hopelessly queenless not wanting to breed from the swarmy mother. I have a queencell which I will put in the hive in a couple of days from a batch that are nearing readiness. (I thought I'd double check for queencells and introduce the cell in a day or two). I also removed the comb and foundation from the 8.5" brood chamber underneath as I needed it elsewhere, leaving the brood chamber. Admittedly the hive was full but the thought in my mind was that bees will die off before the new queen starts to lay thus reducing numbers.

The colony swarmed today. If I was brave I would have left it in the belief that it would come back. However I caught the swarm. In the hive were NO queencells and it was still quite full of bees.

I am pretty convinced that the hive and the swarm are both queenless (Unless a couple of absconded queens popped in from mini-nucs).

Any suggestions as to what is likely?