Well as it is a rumour network, let's have a go
#1 - RAF Tutor retired due to prop failure, no basic pilot training for 2-3 years until new contract/aircraft, therefore PAS needed to mind the gap?
don't tell me they are back flying? If so
#2 - UK to dispose of old atomic waste discretely over some pacific atoll, RAF pilots needed to fly through the fireball. VC-10 can do the role and take 100 pilots at a time, expected to save millions in pensions and scrapping the fleet?
#3 - RAF screws up manning levels by chopping too many newbie pilots? Now that is highly unlikely!