We have rarely had an Oscar favourite as unassailable as Viola Davis. At time of writing, one particularly mean bookmaker has her at 1/66 to win best supporting actress at the end of the month. Alien visitations get better odds.

“I don’t even know what odds mean,” she tells me in a voice that suggests mild disapproval.

She is something else. In Denzel Washington's version of Fences, the acclaimed play by August Wilson, Viola plays the long-suffering wife of a middle-aged garbage man who was once a promising baseball player.

The director makes a charismatic monster of the protagonist. Davis is heartbreaking as the woman who has made his happiness her abiding concern.

There’s more than that one mighty performance to Davis’s strong standing with Oscar tipsters. Now 51, She has been delivering good work for a quarter of a century. She was versatile on stage.

She offered frequent support on telly. Over the last decade – with Oscar nominations for Doubt and The Help – it looked as if she was finally getting her due. She is owed.

Viola's recent wins at the Golden Globes and the Screen Actors Guild were greeted with huge applause. At the former, she spoke eloquently of how Troy, the hero of Fences, reminded her of her late father. Dry eyes were few in the house.

“I always say he was the original Troy,” she says, “I run into so many people who say the same. They have Facebooked me – white people and black people – and they all say that was their father.”

What did she mean specifically?

“He was the original Troy in the sense that, like him, my father had broken dreams. He was 15 years old when he learned how to read and write. He learned it by reading billboards as he groomed horses at the racetrack.

"He never really fulfilled his dreams. I grew up with a father who was hardcore and was just one generation removed from slavery. My father was born in South Carolina in 1936, remember."

If you saw Davis deliver that speech at the Globes then you won't need to be told that she is fiercely articulate and that she can deliver her own lines as powerfully as she does those by the likes of August Wilson. You will also be aware that she has the most extraordinarily resonant voice. What comes as a shock is the degree of presence that swarms around her.

Presence

We meet in the British Academy of Film and Television Arts headquarters on Piccadilly. Davis, who has just enjoyed a retrospective tribute, sits calmly beside a giant replica of the famous Bafta mask. She is still, composed and striking. How odd it is (or is it?) that Hollywood seems intent upon casting her in flattened, unglamorous, older roles.

In person, though serious, she is really quite fabulous. She does, at least, get to exploit that side in the deliciously melodramatic TV series How to Get Away with Murder.

Viola has more to say about her father. She was born in South Carolina, but moved to Rhode Island when she was still an infant. It doesn't sound like an easy childhood.

“He was an alcoholic, but I loved my father,” she says. “I loved my father, but he was a complicated man like Troy is. He bore the weight and the scars of how his father raised him and he carried that on to his children. I don’t see my father’s story being exalted in many narratives.

“I see that in August Wilson’s characters. They are the average black man who would be invisible to anybody else: the janitor, the garbage man, the man who cleans your yard.”

I wonder if Davis still regards herself as a southerner. She grew up in the northeast. She doesn’t have the accent. But all her family are from that part of the world.

“You know what? I do,” she laughs. “I also think of myself as a Rhode Islander. I don’t have the accent, but I consider myself a southerner because of how I grew up: my mom and dad eating pigs’ feet and ham hocks and collard greens and black-eyed peas. Those are the things I cook. I am great at cooking those foods.”

Davis made quite a journey as a young woman. She picked up a taste for acting at Central Falls High School and moved from there to Rhode Island College. By her early 20s she had been accepted into one of the nation's most prestigious acting colleges. Like Jessica Chastain, Oscar Isaac, Kevin Kline and Kevin Spacey, she is a graduate of the drama programme at Juilliard in New York City.

“By that stage I only had the money to apply to one school,” she says. “I thought of NYU, Yale or Juilliard. But I only had the money for one. So I picked Juilliard.”

Those are three pretty prestigious colleges. She set her sights high.

“Oh yes. That’s it.”

Were there many African-Americans in Juilliard that point?

“It was a bit rare at that stage,” she says matter-of-factly. “There were 856 students in music, drama and dance. In the entire school there were 30 people of colour. But it’s changed now.”

I wonder how much the wider entertainment business has changed. Just 12 months ago, the Oscars were caught up in controversy when, for the second time in two years, not a single black person secured an acting nominations. This year, breaking records, seven people of colour (including our own Ruth Negga) are up for performance awards. Something has altered. Is it enough? What’s the feeling from inside the conversation?

“Things have changed in TV, certainly, because you now have 400 television shows on the air. There are stations you’ve never heard of. Because of the sheer volume you have more opportunity for actors in general. Television is the place to be for everyone.”

Things were tougher 25 years ago, but Viola seems to have got by reasonably comfortably. She didn't become a star as a young woman, but that voice and that presence kept her busy on stage and TV. You can spot her in Steven Soderbergh's Out of Sight and Todd Haynes's Far From Heaven. She was an "actors' actor". She was known within the business. All that is very nice, but it doesn't pay the heating bill. Was she always able to make a living?

“Oh, I was always able to make a living as an actor,” she says. “Apart from my first year, which was tough. I had to borrow money from my sister a lot. But I paid her back! After that I made enough money. I never felt like a ‘tragic actor’ even when I wasn’t getting very much work. As long as I was getting some I was happy. I loved it when people asked what I did and I was able to say: ‘I’m an actor.’ I just loved saying it.”

She positively beams and (if one can do so when seated) swaggers when she imagines herself being asked that question. Still, I suspect she understates the struggles she must have gone through.

Something significant changed for her in 2008. Her role as a conflicted mother opposite Meryl Streep's intimidating nun in Doubt won her an Oscar nomination. Two years later, nominated for The Help, she was many bookies' favourite, but Streep made a late rally and triumphed for The Iron Lady. That same year, she won the Tony (her second) for the Broadway revival of Fences.

Celebrity status

Davis could now reasonably regard herself as a celebrity. It had taken her until middle age to achieve that status. It’s not a path that many plan, but, among those who have achieved such late renown, I have met very few who would wish it otherwise.

“Oh, I am most definitely happier that it happened now,” she says. “Because now I have perspective. I now know what it means and I can take it in my stride. I do not let it control me. I’ve been in the business so long I can look at people and say: ‘You know all you are going to get out of that is a picture?’”

What sort of things does she mean?

“Oh parties. Anything that is just a photo op. I have a perspective on all of that. It means everything and nothing to me. For me, right now, this is my third time at the rodeo and I know, as soon as the Oscars are over, you have to go right back to work.”

Davis could give lessons in the art of personal perspective. Having started from humble beginnings and waited decades for full-powered fame, she has had time to clarify what’s important and what’s worth dismissing.

Still, it must be tricky to calm expectations about the coming Oscar ceremony. She may be a huge favourite but Streep is once more among the nominees and, following that veteran’s rousing speech at the Golden Globes, some wind is back in her sails.

“Yeah, it feels good. But once again I know that the noise is going to die down,” she says. “I don’t know if a lot if people understand this, but awards season starts in October and it’s every day. Every day there’s something. You’re exhausted. You’re flying back and forth. Then you get the gold statue. Everything becomes about that. People think it’s going to change their lives and it doesn’t.”

Davis has won two Tonys, a Golden Globe and an Emmy. This year she became the first African-American woman to receive three acting nominations at the Oscars. So she already has a grasp on the pressures.

“Everyone talks about the Oscar curse. There is no curse. This is all about winning a statue. After you win it, you take photographs with it and then you get back to work. And you still have to deliver.”

One of the added pressures this year is that every nominee has to have an opinion on Donald Trump. Davis introduced Streep's already famous Don-bashing speech at this year's Globes. We are all a bit confused by the current madness in the White House. What's going on?

“Listen, when you find out you come back and tell me. Is that all right? Yeah?”

Fair enough.

Defining scenes

Nobody could question the effort that Davis puts into her nominated performances. In The Help, Doubt and, now, Fences, she takes over one key scene that ends up defining the film in many viewers' minds. Few other actors seem so emotionally inhabited by their performance. I wonder if, having appeared in Fences on Broadway, she felt the need to modulate her performance on screen.

“You dial things down if they need to be dialled down,” she says. “But the stakes are high in a lot of these moments. You have the task of making them honest – but still big. I liken it to when my dad passed. I was in the hospice. They put the stethoscope to his chest and said: ‘Miss Davis, he’s gone.’ I didn’t have a small reaction to that.”

That scene in Fences looks to have turned the actor inside out. There are tears. There is even a degree of mucus. It can't be easy to shake off that degree of emotional investment.

“On the set it does cost you something,” she agrees. “It should cost you something. At the same time you need a technique to save yourself. Acting is not rocket science. But it is an art form. It’s a craft. By the time I get home I am done. I may have a cocktail. But that’s about it. Ha ha!”

Davis has been married to the actor and producer Julius Tennon since 2003. In 2011 they adopted a daughter. Life is in harmony. Her profile deservedly boosted, she can now balance prestige projects such as Fences with marquee entertainment such as Suicide Squad. Next year, we will see her in a big-screen updating of Lynda La Plante's Widows, a classic 1980s crime drama, to be directed by Steve McQueen.

“That’s going to be fabulous!” she says, lighting up.

There’s something really stirring about her enthusiasm. I get the sense she still enjoys being able to say: “I’m an actor.” Yes?

“Ah, I liked that better back then,” she says slightly wistfully. “Going round the country to every theatre imaginable. I was living a dream. Who could have problems with that? Who could have a problem with that?”

Who indeed?

THE OSCARS AND RACE

The Academy Awards have a long and complicated history with race. The first African-American actor to win was Hattie McDaniel for Gone with the Wind back in 1940. The Academy has, however, to live with the memory that, even in a relatively liberal city such as Los Angeles, McDaniel was, during the ceremony, forced to sit at a segregated table at the back of the room.

The floodgates did not open. It took more than 20 years for a second actor of colour to grab a statuette: Sidney Poitier won best actor for Lilies of the Field in 1964. Another two decades intervened before, in 1983, Louis Gossett Jr won best supporting actor for An Officer and a Gentleman.

Since then, an intermittent trickle of Academy Awards have gone the way of black actors. Cuba Gooding, Whoopi Goldberg and Denzel Washington won in the 1990s.

In 2002, for the first time, both best actor and best actress went to black performers: Halle Berry triumphed for Monster's Ball and Washington won again for Training Day.

In 2015 and 2016 the Academy faced criticism when not a single black actor was nominated in any category. Cheryl Boone Isaacs (herself African-American), president of the Academy, announced an immediate plan to further diversity among the hitherto very white, very male, very old voters.

But this year's more diverse shortlists – seven actors of colour among 20 nominees – probably just reflect a better selection of available films featuring black actors. Pictures such as Moonlight, Fences and Hidden Figures would have figured in any year.

Elsewhere much work needs to be done. Bradford Young, mentioned for Arrival, is the first black American ever nominated for cinematography. Only four black men (and, yes, they're all men) have been nominated for director.