I think some of the infrastructure maintenance (and maybe general development too) is outsourced. About a year ago I was on a service management training course in London along with some Siemens staff who were working on the iPlayer project.
BBC outsources to Siemens,
This includes handing over all it's unique skills
Siemens, then bills the BBC for stuff it already knew how to do.
Management demonstrates with many Powerpoints how this is saving everybody money.
but don't let that trouble you.