Vanessa Redgrave is crystal clear about what she wants her first film as a director at the venerable age of 80 to achieve. And it is neither box-office success nor awards.

"I want it to save lives," the acclaimed actor says.

A longtime political activist, Redgrave has been so affected by the refugee crisis in Europe that she has made the documentary Sea Sorrow, with son Carlo Nero producing. It's a personal and poetic call to arms that includes her own family's history as "refugees in our own country" during World War II.

As a three-year-old in London, Redgrave remembers hearing the blaring of an air raid siren then being evacuated to a relative's home in Herefordshire when Nazi bombs began hitting the city in 1940.

"I was a child in the war and people needed protection," she says. "We needed protection as children and we needed people who were kind to us.

"My producer encouraged me to tell my personal narrative because it would help people see that what has happened to me is happening to so many people – younger, older, babies, you name it.

"These are doctors, these are engineers. These aren't 'them'. They're 'us'."

Over a dazzling stage and screen career, Redgrave has won an Oscar – for Julia in 1978 – from six nominations, two Emmys and a shelf full of Golden Globe, Tony and Olivier awards. Her films include A Man for All Seasons, Blow Up, Camelot, Isadora, The Bostonians, Howards End, Mission: Impossible, Atonement and, more recently, The Butler and Foxcatcher.

A member of the famous Redgrave acting family – daughter of Michael and Rachel, sister of Lynn and Corin, mother of Joely and Natasha Richardson and mother-in-law of Liam Neeson – she has long been outspoken on human rights issues including the plight of the Palestinians and her opposition to how governments have handled "the war on terrorism".

The spark for Sea Sorrow was that shocking image of a Syrian boy lying dead on a Turkish beach in 2015.

"The terrible wars that are producing the refugees have been going on for a hell of a long time but there's always a catalyst that finally says you've got to do something more," Redgrave says. "I saw the picture that a Turkish photographer took of Alan Kurdi​, a Kurdish baby boy, who drowned along with his sister and his mother coming from Kobani, a town which had been under seige from ISIL, ISIS, Deash or whatever you call them.

"They tried to get protection and cross the seas about two miles wide. According to the law, they should have been given free transport on the ferry to cross to Kos but they weren't. No refugees are given the kind of help they ought to get. That's why so many are dying."

Part of the shock was that the boy was just three years old when he needlessly died after a small boat carrying 16 people capsized.

"It was was such a narrow crossing," she says. "And, worst of all, it's a commercial crossing. They should have been given free tickets to get the little commercial ferry to the Greek islands."

Redgrave decided a documentary was the best medium for a cry from the heart.

"Film can communicate in a unique way," she says. "There are some people who care but there are some people who don't care, who've got hardened. And there are some people who are just hard.

"So we felt we should make a film and we spent every penny we've got to do it."

Sea Sorrow features Ralph Fiennes reciting a passage from Shakespeare's The Tempest that powerfully echoes the plight of modern refugees. He talks about being hurried aboard "a rotten carcass" of a boat so poor "the very rats instinctively had quit it" and sent out to sea.

Redgrave also visits the infamous "Jungle" refugee camp at Calais, reeling away after peering inside a shabby tent that is home to a family of four.

"Disasters are happening to refugees in the deserts and, above all, in the seas – the Adriatic and the Mediterranean – because of [government] policies," she says. "People are dying who shouldn't be dying and who have a right to live and a right to protection."

Redgrave almost simmers about the slow government response to the crisis.

"The European governments including my own are very, very slow," she says. "In fact, we have to take them to court to make them do what the law says they must do."

Redgrave knows Australia has been struggling to deal with the refugee issue, too.

"I consider myself a citizen of the world," she says. "Of course I'm not, I'm a British citizen. But I was a child in the world war and I saw everywhere as the world.

"Culturally I was brought up to want to know what's happening in the world and to follow the news and to read international writers and to want to know what foreign companies are doing in the theatre and new films that are being made. I didn't have that very restricted view of 'oh, I only care about what's happening in my little backyard' sort of thing."

Redgrave wants Sea Sorrow to have an impact on governments around the world.

"As [former British Labor MP] Alf Dubs is always saying, governments listen to public opinion," she says. "If governments realise that public opinion is very, very, very keen on a course of action, they will usually follow it and do a U-turn.

"Governments don't seem to have much education, much culture, much awareness of their own people anywhere. I don't understand what happens, why they don't understand more or care more. They have such limited vision when the stakes affect everybody.

"But we will influence many people, I know. It's not difficult. What's going to happen to us when it's our turn if we don't help anybody?"

Redgrave does not hold back on how the Brexit vote has influenced Europe's ability to deal with the crisis.

"Brexit is a catastrophe," she says. "An absolute catastrophe. It was a very narrow majority that voted to leave Europe.

"But they weren't told the truth. And nobody – in government and so on, and the opposition parties – told them really what was going to happen.

"I don't see why this has got to be a forever situation. But this is the world we're in. We must look to our neighbours and care about them."

Redgrave says with a laugh the she found directing for the first and last time difficult.

"But I had good advice. I had a good producer, my son, a good editor.

"We worked [with people] who were terrifically helpful. Everybody gave themselves to it, either asking for a very low fee or doing it for nothing, including Ralph Fiennes and Emma Thompson and some of the other actors."

The veteran actor is looking forward to travelling to Australia to launch Sea Sorrow at the Sydney Film Festival.

"My grandfather died in Australia, aged 51," she says. "He was an actor. He came out to seek his fortune and he spent it on drink."

Needless to say, Redgrave is putting her energies to something much more productive.

Sea Sorrow screens at the Sydney Film Festival on June 17 and 18. Vanessa Redgrave will appear at both the festival and Vivid Ideas.