Peter Blake is an agent with MI6.
Blake came to the department after putting in several years in the British SAS, reaching the rank of sergeant indicating he was there for likely more than one tour of duty. While we do not know exactly how long he has been an agent, it is certainly long enough to have acquired a reputation for getting the job done such that he has for the past four years been assigned to work directly under the control of the Director of Operations and not through the normal bureaucratic structure at Vauxhall Cross. In fact, that Director has taken to setting up his own operations in a "clandestine office above a small antique shop" and not at the Legoland headquarters. This move was done to protect 'C', the head of MI6. "In these days of transparency and accountability, the Director rightly felt that the less [ C ] knew of the illegal elements the better."
Blake is described as 43 years old, still quite fit, standing 6'2". He has "short dark hair, steely grey-blue eyes, and a square, determined jaw". Elsewhere it mentions that he has a chiseled face. He commonly sports dark attire such as a black bomber jacket, t-shirt, and jeans. In his off time, he enjoys sipping on Jack Daniels on the rocks and spending time with Theresa, a mid-30's woman who has gone back to college to major in journalism.
On the job, Blake routinely partners with CIA operative Brad Samson. Again it is not known how long their association has been going on but it is long enough that they have established a well-defined connection and can anticipate each other's actions and trust that they each have the other's back covered.
"Life is nothing without adventure", Blake once commented to his boss upon being told there was a new assignment for him.