What's this TV show?

[cheebacheeba]

So I was REALLY tired the other night...as I went to bed I had the TV in my room on, and saw a bit of a show.

Info:
It was a UK show.
The main character was named John
In the scene I saw, he entered an apartment with two larger men, saw a guy that was there and said something along the lines of "I'm not staying here, he's an idiot".
The guy he was referring to was a former cellmate of his.
Apparently John was himself extracted or had release organised from prison earlier than the part I saw.
The two large men wanted John to use his skillset to ???
One of the larger men instructed the other one to kill the former cellmate if John didn't comply, who then starts strangling the other guy from behind with a wire or something.
"You need to ask yourself - Do you think I won't do it"
He agrees. Guy lives.
The next scene was the morning after.

...It looked quite good, whatever it was. Wouldn't mind grabbing it.