There are only 3 scenarios in which outsourcing may make sense:
[a] where economies of scale can be achieved - unlikely if 1,400 staff are involved;
[b] where the 'sale and leaseback' of staff can be used to provide a cash injection that can keep the annual bonuses rolling long enough for your golden parachute to kick in - not applicable in a non-profit like the Beeb; and
[c] where IT management is FUBAR - but then the obvious course of action is to sack the clueless bastards and employ someone competent.
The Beeb have obviously discovered:
[d] leaping onto a bandwagon whose 'sell by' date is long past.