It is a true story of class, intrigue, and the treachery of male friendship. So who better to play the leads than two of the acting world’s most celebrated Old Etonians?

Dominic West and Damian Lewis have been cast in a major new television drama about the life of Kim Philby, the British intelligence officer who betrayed his country — and colleagues — to leak secrets to the Soviet Union.

West, 50, will play Philby, while Lewis, 49, takes the part of his close friend Nicholas Elliott, an MI6 officer who always defended Philby against accusations that he was a Russian double agent until the truth of the charges became undeniable.

The two actors are friends but have never before shared the screen, which will add to the anticipation.

The series, A Spy Among Friends, is the first original drama commissioned by Britbox, the subscription streaming service launched by ITV and the BBC as a rival to Netflix.

Producers and managers hope that it could become a multi-series Cold War espionage saga that could get viewers hooked on Britbox just as The Crown has done for Netflix.

Patrick Spence, the executive producer, said it would differ from previous screen portrayals of the Cambridge spy ring by focusing on the human story of Philby’s betrayal of Elliott. Both intelligence officers were educated at public schools; the stoicism and emotional complexity of Britain’s upper classes will be one of the drama’s themes.

The two actors are friends but have never before shared the screen, which will add to the anticipation.

In 1963 Elliott was dispatched by MI6 to confront Philby with evidence of his treachery and obtain a confession. “I once looked up to you. My God, how I despise you now,” he told his former friend. Philby defected to Moscow shortly afterward and died in 1988. Elliott died in 1994.

West and Lewis were the obvious first choices to play the leads and “luckily” both accepted, Mr Spence, creative director at ITV Studios, told The Times.

“They are both superb actors, they come from a world not entirely dissimilar to Philby and Elliott,” he said. “And they are both very good friends of each other, but have never worked together. So there was that thrill too.

Out in the cold: Philby and partner Melinda Maclean walk in the woods outside Moscow in the 1960s, after he defected.

“Philby was a traitor and man responsible for the deaths of thousands of people. But in a drama you still need to see the humanity of him, to understand what makes him tick. Dominic has demonstrated time and again that he can play characters that you would potentially describe as evil, but give them humanity.

“Elliott’s journey is a very emotional one. His journey of discovery, and making sense of his best friend having lied to him all that time, is one we felt Damian would play really well.”

The drama is based on the bestselling book of the same name by the Times columnist Ben Macintyre.

It was adapted by Alexander Cary, a former British Army officer turned television producer who co-wrote the US spy thriller Homeland, which starred Lewis.

His script was snapped up by ITV Studios, the commercial broadcaster’s production arm. The show attracted bids from several broadcasters and streamers but Britbox “came after it hard”, Mr Spence said.

The on-demand service, which is 90 percent owned by ITV, was launched last year offering classic British series such as Downton Abbey, Broadchurch and Midsomer Murders.

The Philby thriller has been delayed by the coronavirus but production is expected to start shortly, with filming planned in at least three countries. “It will feel high-end and classy,” Mr Spence said. “It has a budget to suit the ambition of the piece.”

West and Lewis have starred in some of the most prestigious television dramas of the past two decades. A Spy Among Friends, which also has a female lead whose identity is being kept under wraps, is due for release next year.