He too is very 'laddish' and likes being a Police Officer for the associated perks. Like Kray, he is intelligent, hypocritical, cynical and pragmatic. He sees no reason why Police Officers should not take liberties such as staging pub lock-ins, using the car siren when late for lunch, or even planting evidence on clever criminals if that's what it takes to get a conviction.
Arguably more aggressive than Kray, Boyle sometimes covers up for Grim's mistakes or steers him in the right direction, all the while being generally unimpressed with his superior. The second series, with Boyle, is a bit more serious in this regard and shows CID as more involved than the first series. Boyle has several spots in this and as such, his character is more developed than Kray's but perhaps proportionally less comical.