Becky Gamester-Newton, for BT.com, interviewed actors, writers, and so on regarding Season 2 of COBRA.

What Robert Carlyle had to tell the journalist about
how he studied politicians in real life is of interest. Quoting:

"You don't necessarily go and find a politician and stick that mask on your face to mimic any particular person,
but you can look at a mass of them," said Robert Carlyle.
He added that the late Labour leader John Smith provides inspiration for him, for both the role and in a general sense.
"The one that stood out for me was John Smith, the old Labour leader of the 80s and 90s who passed away.
The best Prime Minister we never had, in my opinion. He was a fantastic man.
I think what Smith had was a real sense of the moral compass.
[COBRA leading character, Prime Minister] Sutherland is what would be described as a kind of two-tier, utilitarian politician,
and I think that's possibly where Smith was as well.
I think that fundamentally he was about what was doing the right thing.
But he was pragmatic at the same time, and I think he understood that.
The problem for the Labour Party back in those days was that it was so different from the Tories at that time.
The Thatcherism of the time was so extreme, and the Labour Party, through Kinnock, was so different.
But Smith was a pragmatic man and he understood that I think,
and he knew that things had to slightly go not too centrist,
but I think he realised that they had to make a few steps that way."

link:
COBRA Season 2: secrets from the set