Sir Malcolm Rifkind has said that security chiefs speaking to MPs in public today was "an historic occasion" that will be repeated.
The Chair of the Intelligence and Security Committee added that he believed those involved were glad of the chance to speak publicly.
He said: "Many of them have been upset at the accusations that they have been doing something improper or doing something unreasonable to their fellow citizens.
"I suspect they were pleased to have the opportunity in public to speak about the work their own staff do and how important it is to the national interest."
More top news
She caused as much of a stir with her pout as she did with her baking - so could lipstick be a sideline for this year's Bake Off winner?
Rain will slowly edge into Scotland, reaching Northern Ireland by Thursday afternoon. There will be plenty of cloud across the UK.
Clashes between rival supporters marred West Ham's EFL Cup fourth round win over Chelsea at the former Olympic Stadium