Stupidity at it's best
I'm not sure what is more incredulous - the fact that people in power believe that back door encryption keys are a good idea, in that I blame the political parties and some very stupid civil servants and contractors who think it could ever work especially when most of these companies are outside of the UK.
Or the fact that "terrorists" are just building their own, ironically open source, encryption software (hence the reason India recently blocked Github) and are, I would guess, probably unlikely to want to hand over the encryption key for the "intelligent" services in the UK.
I wouldn't trust ANYTHING the supposed spooks told me especially when they have a vested interest in their own budgets.