Fresh from appearing in his first Doctor Who scene as the Fourteenth Doctor earlier this year, and from appearing in Staged season 3 mere weeks ago, David Tennant will next be seen in ITVX drama Litvinenko.
In the drama, Tennant will play the title role of Alexander Litvinenko (also known as Sasha), a former Russian spy who was poisoned in 2006.
As heard in the show's first trailer, Tennant will be using a Russian accent for the series, and when speaking exclusively with RadioTimes.com, the show's director Jim Field Smith revealed it was a tricky aspect of the character for Tennant to nail down.
Smith said: "David does a lot of prep, he comes to set fully prepped. And he was very keen to nail down the particulars of the character before we got anywhere close to shooting it. It wasn't something where we were going to kind of explore it in the moment that you might do in a fictional piece."
Smith continued: "The tricky thing was there are very, very, very few recordings of Sasha actually speaking English. So we had to kind of extrapolate what he sounded like speaking English through speaking to Marina and through speaking to the detectives that interviewed him at the time.
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"Because it's not just about how Sasha sounded, it's how he sounded in the condition that he was in. Although he spoke surprisingly good English, he generally didn't speak English that much and most of the recordings available of him he's speaking Russian, which obviously wasn't that helpful.
"Because the most extraordinary thing is that Sasha conducted most of his interviews with the detectives in English, it was only when his health really started to fail or he couldn't find the right word that he would converse in Russian through an interpreter, but most of his interviews were in English."
Litvinenko also stars Margarita Levieva, Mark Bonnar and Neil Maskell, with Levieva recently telling RadioTimes.com that Tennant is "remarkable" in the series.
She said: "Just as an actor, he's such a stunning artist. And we didn't meet until on the day when we were shooting the hospital scenes.
"And one of the gifts that Jim Field Smith gave us, the director, he said, 'I just want you to come in as these people and I'm going to step away and just give you the space to really embody them and to live out the story.'"
Litvinenko arrives on ITVX as a full boxset on Thursday 15th December.