Ask anyone in the industry and they will tell you filmmaking is a peculiar business. But just imagine trying to be creative during the Blitz - that is the premise of rom-com Their Finest.

Directed by An Education and One Day's Lone Scherfig, it is about an untested female screenwriter (played by north Kent actress Gemma Arterton) trying to make propaganda films in difficult circumstances in 1940.

It is based on the novel Their Finest Hour and a Half by Lisse Evans, a former television director whose work includes Father Ted and Room 101.

Speaking to us on the red carpet at the film's premiere at BFI London Film Festival, Evans said: “I had always had an interest in the home front, which is what happened in this country during the war. I read a book about it when I was 14 and have been obsessed ever since.

“And also I worked in television for quite a long time and when I became I writer I felt I wanted to write about this particular world behind the camera where people are obsessed with trivial things and it takes 12 people to decide the colour of a man’s tie.

“And I thought I could combine the two – was it the same when there were bombs dropping outside the studio?

“I did some research and found that yes, all the egos, all the rivalries, all the difficulties were all exactly the same. So it combined both a passion of mine and something that I know about.”

For Scherfig the attraction was the source material and the script adapted by Gaby Chiape.

The Danish director said: “It is such a dramatic world. It is a world where things constantly change, as things did at that time, and where films had never been more important and they made a big difference.

“There are great characters and then there is a lot of humour, which I really enjoy.”

Having a funny, dramatic script and a highly acclaimed director meant a quality cast was also attracted to the project. Led by former Gravesend Grammar School for Girls and Miskin Theatre pupil Arterton, the line-up of Great British names includes Hunger Games and Me Before You leading man Sam Claflin, Caterham's Love Actually star Bill Nighy, Eddie Marsan and Richard E Grant.

Speaking to us at the premiere, Grant was very clear as to what made him get on board.

“Lone Scherfig and the cast – Gemma Arterton, Sam Clafin and Bill Nighy, who is hilarious to work with,” he said. “He has the best stories of any actor you could wish for. It was a very enjoyable job to do, so I hope the film is good.”

Grant added: “I play a very dry old crusty fart of a character who is head of the Ministry of Information who makes propaganda films in the Second World War that are supposed to be anti-Nazi.

“He has a very dry sense of humour but he is a bureaucrat and a bore, so perfect casting.”

Scherfig said: “I think it is because you have that kind of script that you can attract a cast of this level.

“They can see these are great characters, that they get to do something that is witty and scenes that become moving within seconds.

“That change we know really works well in England and we know from the Toronto premiere that it also travels.”

There is no doubting the extraordinary talents of Their Finest's ensemble but it was the leading lady that pulled everything together.

Author Evans said: “She’s fabulous. She is both beautiful and touching and also the character has a real growth throughout the film and I thought she did it absolutely beautifully.

“The character at the end is nothing like the character at the beginning. We all know films are shot out of order and she somehow managed to give that lovely trajectory.”

Their Finest was screened at BFI London Film Festival as the Mayor of London's Gala. It is at cinemas nationwide next year.

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