Tom Blake is an agent with Echo 17.
That organization is "a black ops intelligence-gathering Special Forces unit with a counter-terror and espionage role. Specifically it's a unit that operates behind enemy lines and covertly in foreign states, specializing in the extraction of intelligence from high value human targets, often in places where Britain and its allies have no jurisdiction. Our existence has been veiled even from MI5 and MI6 for the obvious sensitivities."
It had been originally set up to answer directly to the Prime Minister but over time apparently the worry about the U.K. leader having essentially his own 'army' unit got too untenable so the organization was marked for disbanding. "A victim of a nervous government and budget cuts. Somehow [the] commanding officer, Harry Patterson, had convinced MI5 to bring the unit under the auspices of the service."
Blake is an operative with the organization but he is an rather unique. He is described as "a bit of a cold fish" and "cantankerous". He came to the group via his medical profession being first a military psychologist. It was considered that someone with his intelligence and background "would be an invaluable asset for an organisation battling against a mounting home-grown terror threat." One of his more interesting assets is his technique for interrogation for which he "devised a method of rapid hypnotic induction which has proved so far to be around ninety-five per cent effective".
Blake is not, however, just an interrogator or a desk man. He gets out in the field himself and has shown many times over that he definitely belongs there. He prefers to work alone when he can, pointing back to the cold fish comment, but he can play well enough with others.