Thanks @JeffH and @Peter48 have moved hive to sons place tonight.
This is the same hive as discussed in Walk away worries
As per that thread I have been performing preemptive swarm prevention on hive but the split was attacked by robbers on 26th Sept. and I placed a robber screen and closed screen entrance, left split closed up for 3 days, opened entrance on 29th some activity at entrance during the week. Checked split yesterday, no queen - dead pupae in capped queen cell torn open, no stores or larvae, 2 frames of bees so decided to recombine with parent hive using newspaper method. As it was 3:00pm I decided not to inspect brood on parent hive and it swarmed this morning.
So in summary
26/7/18 1 frame replaced with foundationless frame
22/8/18 1 frame replaced with foundationless frame
10/9/18 2 frame replaced with foundationless frame / made split
24/9/18 1 frame replaced with foundationless frame / added to split
The flow super was on and just started to see nectar in observation window, so I did try but the hive still swarmed.
As I have observed the main swarm how long before a caste swarm?
Edit: date change