Ben Swan is an agent with MI5.
If you worked with him in that government agency, you would likely know him as Julian Lawson. That is his covername now, the one that his fellow operatives would be told was his and they would use it though they would not believe it to be true. Certainly the names they used around him were equally bogus. He is not happy with such deception. His bosses are not concerned with his acceptance of it so long as he uses it.
We are told early on that "Four months earlier, Lawson had operated in a different environment and with a different name. His correct birth name was Ben Swan. He had been a serving police officer with only a vague knowledge of MI5; a career detective operating in the CID and other specialist departments within the service. For the previous two years, he had been a member of the Counter-Terrorism Directorate, operating throughout the UK and with frequent visits to both Southern and Northern Ireland."
Recently, though, his line of employment has been changed when he is "recruited by the UK Security Service, also known as MI5. His police rank is suspended and he operates as a full member of the Service. He is given a new cover identity. His police background is not disclosed to his new colleagues. In accordance with MI5 policy, all members operate with a cover identity."
This is an interesting aspect to his new job - his knowledge of police procedures and methods are vital to his being able to do his work properly but how he came to have that knowledge is considered a secret from his fellow agents just as the source of their skills will be kept from him. Certainly this will help maintain security should any one of them get caught by any enemy and interrogated but it does chafe. Harder still is the fact that Swan is not allowed to mention to anyone outside his ranks who and what he works for nor what his job entails. Swan decidedly not used to operating so covertly.
Swan is likely in his late 30s having worked at CID for quite a few years. He is a widower, his wife of 10 years had died from cancer just over a year earlier.