The Prime Minister has reasserted the rule that the security services cannot spy on MPs and confirmed that the same principle protects AMs and members of other devolved parliaments.
David Cameron's ruling follows a court case in July, when it emerged that GCHQ guidance had been revised and that AMs were no longer protected by the so-called 'Wilson Doctrine'.
It was named after the Labour Prime Minister Harold Wilson, who decided in 1966 that MPs could not be spied on. However, in a letter to the Assembly's Presiding Officer, Dame Rosemary Butler, Mr Cameron makes clear that he could give special permission in exceptional circumstances.
In a concession to the fact that policing is devolved in Scotland but not Wales, the Prime Minister adds that if the spying was to be carried out by Police Scotland, he wouldn't be consulted. It would be entirely up to the Scottish Government whether to over-ride the 'Wilson Doctrine'.
The MI6 Spy, Gareth Williams, has been described today as "something of a prodigy" by his former boss.
Stephen Gale, Mr Williams' boss at GCHQ in Cheltenham, has given an insight into Mr Williams' professional life at the inquest into his death.
Mr Gale described how Mr Williams was hailed as a "world class" intelligence officer by his colleagues.
He also described Mr Williams as a "private individual" who rarely attended social gatherings but was fondly remembered by colleagues for his "warm smile" and sense of humour.