MAMMOTH SCREEN FOR ITV ENDEAVOUR Series 9 Film 1 Pictured:SHAUN EVANS as Endeavour and ROGER ALLAM as DI Fred Thursday.

“Shaun and I had the most enormous fun. I’ve never had a relationship like that before with another actor and I can’t imagine having one again. So I don’t think the end of Endeavour will really hit me until it comes around to that time of year when we should be filming,” Roger Allam admits.

We are chatting at ITV’s London hub about the final series of Endeavour which airs on February 26, read about it here while acknowledging the incredible achievement of one of ITV’s most popular TV shows’ and it’s global audience (it’s watched in 200 territories worldwide) over the past 10 years.

MAMMOTH SCREEN FOR ITV ENDEAVOUR Series 9 Film 1 Pictured:SHAUN EVANS as Endeavour and ROGER ALLAM as DI Fred Thursday.

“Making those memories is what has been so wonderful,” Roger adds. “We developed the most wonderful group of friends and actors, who became like family over the years. It has been an absolute pleasure to work with them, especially me and Shaun (read Shaun’s interview here) because we did so much together and had a rapport from the very beginning.

Shaun and I had the most enormous fun. I’ve never had a relationship like that before with another actor and I can’t imagine having one again.”

Coming from someone suspicious of signing up for any long term TV projects, this is quite an admission, but then Roger Allam is allowed to be nostalgic and emotional, considering he’s been in all 36 episodes of Endeavour.

MAMMOTH SCREEN FOR ITV ENDEAVOUR Series 9 Film 1 Pictured:SHAUN EVANS as Endeavour and ROGER ALLAM as DI Fred Thursday.

“I’d have run a mile if you’d told me that at the beginning,” he accedes. “I only intended to do the pilot, and when I heard there would be three series my heart sank. Shaun was just as twitchy because you don’t want to feel trapped.

“I suddenly realised this was the last scene that I would ever speak as Fred Thursday again”

“But as Endeavour went on and the relationships between the characters developed, especially with Shaun, it felt good and natural, even if it meant closing the doors on a number of other things I would have liked to do.”

So how does it feel bringing this enormous chapter of his life to a close? “The last episode of Endeavour was very moving and emotional because I suddenly realised this was the last scene that I would ever speak as Fred Thursday again,” Roger says.

MAMMOTH SCREEN FOR ITV ENDEAVOUR Series 9 Film 2 Pictured:ROGER ALLAM as DI Fred Thursday.

And yet DCI Thursday is someone Roger Allam has made his own – a war hero and family man who works hard and doesn’t give much away – taciturn, reliable, grounded, brave, implacable, with a violent streak that can arise when tracking down some of Oxfordshire’s more dangerous criminals.

So how much of Roger is in buried in there? “My grandfathers were in WW1 and my uncle was killed in WW2,” Roger says. “I was born in the 1950s and my earliest memories are playing in the bomb sites in the East End in London, so we were a very similar class of people to the Thursdays and I used a lot of that, not altogether consciously but it was there when I needed it,” he acknowledges.

“it was a bunged up generation and the things they had seen and experienced came out in violence”

“But I also did some research on soldiers’ experiences in the war and what it was like when their comrades were shot and sprayed with their blood, which are all things to keep in mind with Fred, and I think that’s why he could be so violent.

“Because it was a bunged up generation and the things they had seen and experienced came out in violence. Fred says back in the early days ‘I didn’t tramp half way around Europe to come home and find it being run by spivs and chancers like you,” so I think people who have experienced real violence are quite explosive.”

Pictured:SARA VICKERS as Joan Thursday in the last series. ITV pic

Does Roger like DCI Thursday then? “Oh yes, but he has been through fire and to me he was an Attlee man aiming to create a better world for ordinary people. His policing is a way of protecting that, and his family, which is his foundation in its sense of warmth and love.”

And what about Endeavour and his daughter Joan’s will they/won’t they story line read our previous interview with Joan (Sara Vickers) here “As a father I don’t think Fred is aware of it. There is nothing in the script that says he is, so I assume he was not.

“as a father Thursday might prefer Joan to marry someone a bit more solid than endeavour”

“And as much as Thursday loves Endeavour he he has seen him being really flaky with women and walking away from steady relationships, as well as drinking too much, so as a father he might prefer that Joan marries someone a bit more solid.

MAMMOTH SCREEN FOR ITV ENDEAVOUR Series 9 Film 1 Pictured:SEAN RIGBY as DS Jim Strange.

With interest in the series so high and the characters so beloved, why stop Endeavour now then? “It was the right time. Everything has to have a beginning, a middle and an end and Endeavour has that. You can’t really ask for more than that in terms of drama and storytelling.”

“We went out on a high which means the final series is very satisfying with huge emotional heft”

“We went out on a high. We had already done more films than Morse and Lewis, so we knew this would be the end and Russell has come up with such a credible ending that explains everything really well – which means the final series is very satisfying with huge emotional heft.”

MAMMOTH SCREEN FOR ITV ENDEAVOUR Series 9 Film 1 Pictured:SHAUN EVANS as Endeavour and ROGER ALLAM as DI Fred Thursday.

“But I will miss Oxford. It was always a great pleasure filming there, and yes I’ve kept Thursday’s hat, it was very sentimental.”

So what was the best bit after 36 episodes over 10 years? “I got to cough up a bullet just like Clint Eastwood,” Roger laughs. “It doesn’t get any better than that.”

Endeavour, Sunday February 26 at 8pm, ITV1.