From Love Actually to Harry Potter, Bill Nighy is one of Britain’s most celebrated actors.

It’s something of an in-joke then that his latest role, in Danish director Lone Scherfig’s World War II dramatic comedy Their Finest, casts him as a fading film star.

Looking dapper in a navy suit and pale blue shirt unbuttoned at the collar as we meet in a suite at Melbourne’s Olsen Hotel, Nighy laughs at that backhanded compliment.

“The joke is they were looking for somebody to play a chronically self-absorbed, pompous actor in his declining years and they came to me.”

Adapted by Gaby Chiappe from the Lissa Evans novel set in 1940 in blitz-bombarded London, Nighy plays frustrated actor Ambrose Hilliard.

He’s thrown a lifeline by the propaganda films designed to raise the spirits of a British population facing the full force of the Luftwaffe.

Hilliard is at first a little huffy that his lines for a Dunkirk-inspired feature film-within-the-film are being handled by a woman, Catrin Cole, played with determined pluck by co-star Gemma Arterton.

“In 1940, the men, the screenwriters, referred to women’s dialogue as, ‘the slop’,” Nighy looks incredulous, eyebrow raised.

“Apparently the other term they used quite regularly was ‘the nausea’.”

A great period of change in Britain, class divisions were wobbling as everyone mucked in together and women stepped into roles traditionally held by the men who had gone to war.

“Once you’d let that genie out of the bottle, there was no putting it back,” Nighy says.

He acknowledges that the progress started then still has a long way to go.

“I was fortunate that I was born into a period of great change in that area and I kind of just joined that flow. I don’t take it for granted, but I am very accustomed to the idea of absolute equality.”

Nighy sees common ground in Their Finest’s march towards women’s rights with the progress of LGBTIQ and working-class people in his previous film Pride, in which he played a closeted miners’ union leader.

“Pride was a very important job for me, I was desperate to be in it,” Nighy reveals.

“If I were to tell my grandchildren which social developments was I most obscurely proud to have been around for, I would reach for the emancipation of gay men and women.”

Both Pride and Their Finest champion equality without being deadly earnest.

“Information travels very, very swiftly in joke form,” Nighy notes.

“The thing I like about Pride and Their Finest is that, whatever else they are there to do, they don’t forget to entertain you. They constitute a great night out. That’s the groovy thing about this film, that it’s funny.”