Operation Mincemeat's Kelly Macdonald prefers ensemble work to 'challenging' Line of Duty (exclusive)

Watch: Kelly Macdonald compares Operation Mincemeat to Line of Duty

Kelly Macdonald says she is "much happier in an ensemble" cast like Operation Mincemeat rather than taking centre stage, like in her Line of Duty interrogation scene.

The 46-year-old told Yahoo that her guest lead role in the blockbuster BBC crime series was "challenging but very rewarding", despite the intense pressure.

Operation Mincemeat sees Macdonald's character Jean play a key part in a stranger-than-fiction Allied plan to fool the Germans and conceal their plans to attack Sicily.

Read more: Vicky McClure hints that Line of Duty will be back

It's based on the true story of an elaborate ruse in which British forces used a corpse with a false identity to convince the Axis forces to divert military numbers away from Italy.

Much of the film's action takes place in the covert team's basement operations room, which created a pressure cooker atmosphere for the actors on set as well as their characters.

Macdonald said: "I'm much happier in an ensemble where everybody is in the room doing their own work. It was a great set and we were in there for quite a while. I think the art direction was incredible.

"But Line of Duty was bright lights and stark and it's just talking. It was challenging, but very rewarding."

Read more: Kelly Macdonald still hasn't watched her Line of Duty series

In the sixth series of Jed Mercurio's show, Macdonald played DCI Joanne Davidson, who came under the suspicion of anti-corruption unit AC-12.

She received acclaim for her performance, including in a lengthy and revelation-packed interrogation scene during the penultimate episode of the series.

In Operation Mincemeat, Macdonald's Jean is a figure of affection for both key architects of the plan — likeable flight lieutenant Charles Cholmondeley (Matthew Macfadyen) and married intelligence officer Ewen Montagu (Colin Firth).

Jean and Montagu bond as they work out the details of their fake airman's backstory and this seems to push them into romance, despite Montagu's status as a married man.

Read more: Colin Firth revisits Bridget Jones's Diary

Macdonald describes the chemistry between the duo as "a very innocent love affair" informed by the excitement of helping to build a deception together.

She said: "The lines [between reality and their deception] are blurred slightly and I think it's depicted really sweetly in the film actually. It doesn't go too far.

"If it was a Hollywood film, it might be something else entirely. It was a great part to play. I had basically two Mr Darcys."

Operation Mincemeat also stars Johnny Flynn as James Bond author Ian Fleming and Jason Isaacs as Admiral John Godfrey — believed to be Fleming's inspiration for spy boss M.

The movie is directed by Shakespeare in Love's John Madden from a script by Michelle Ashford, adapted from historian Ben Macintyre's non-fiction book.

Read more: Operation Mincemeat director pays tribute to Paul Ritter

"We were the little moles in a basement scurrying around and coming up with outrageous plans," Macdonald said.

Operation Mincemeat opens in cinemas in the UK from 15 April.

Watch: Trailer for Operation Mincemeat