Bait hive success - with a QE twist

This year I placed a hive, populated with brood frames and super frames divided by a QE, on some spare ground away from the apiary.

Would it attract a swarm? For the first time in 15 years, YES! 

In fact, I had largely forgotten the hive, and only checked from time to time. When I noticed a ton of activity, it was at the roof, not the entrance. Ambling over to check, I found a full swarm and queen. 

The bees had chosen the roof vents as their preferred entrance, and then clustered in the super. When I looked through the hive, I found the Q isolated, walking around by herself below the QE.

My guess is that the swarm wriggled through the vents, but the Q was too big, so she flew in the normal way, and the bees had not figured out that they needed to move down. 

Anyways, I blocked the vents and the foragers soon switched to the main entrance. After a week I looked again, and the Q is now laying in the brood box.