I had a quick look on thebasource and it looks to have started at the end of Nov. There were no swaps to 3 class in Oct, once in Nov, 4 times in Dec and 4 times thus far in Jan (3 times in last 3 days).
I’ve a 2-4-1 booked in CW next month, now starting to worry that we’ll end up in WTP; worse than F to J in my opinion as I’ll lose the bed.