For practically all my professional life, I have met and written about show people. Big stars, too, like Fred Astaire and Gregory Peck. But none of those experiences ever compared with being with Vera Lynn.

Only weeks ago, I was sitting in the living room of a house in a leafy road in East Sussex, talking to a woman who, as a young child, I had heard singing We’ll Meet Again seemingly every time my parents switched on the brown mahogany box they called the wireless. When she offered us Yours, we believed that she was “Ours”. Such memories don’t fade.

And now, a week and a day before her 100th birthday, I can add to those memories the three times that she and I talked for a BBC Radio 2 programme. On each occasion, there she was, sitting bolt upright in a chair, playing with her dog, Digby. (He wouldn’t eat until she said “OK”.)

She was made a dame of the British empire in 1975 but it’s difficult to call her “Dame Vera”. Oscar Hammerstein once wrote “There Is Nothing Like a Dame”, and there has never been one like this dame.

To her nieces, whom I also interviewed, she remains simply Auntie Vera. If she hasn’t been everyone’s sweetheart, she has, perhaps, always seemed to be their auntie.

Before we met, a couple of people close to Lynn told me that there was a time when the BBC thought she ought to have elocution lessons. Thankfully, the lessons made no difference. How could they? As she told me: “I’m a girl from East Ham.” And girls from East Ham sounded like that and saw no reason to change.

Lynn has never learned to read music. But she always studied the scores of her songs. “I asked her why,” said the former choreographer on her old TV show, Dougie Squires. “‘Oh, I just look at the dots,’ she said. ‘When the dots go up, I go up. When the dots go down, I go down.’”

Vera Lynn in 1942. Photograph: Keystone/Getty Images

She was worried when we met that she couldn’t remember things. Not true. She was as bright as the proverbial button, her speaking voice as strong as in the days when she entertained the troops of the “Forgotten Army” in Burma 75 years ago and assured them that yes, we would “Meet Again”.

I asked what it felt like being made a Companion of Honour only weeks before the Queen described Lynn as her favourite singer. “Golly,” she answered, “they’re both very important to me, but on a different level. That the Queen has chosen me as her favourite singer – that, in itself, is an honour.”

Of course, it was during the second world war that she really made her name. In a way, she seemed to be part of Winston Churchill’s war effort.

The songwriter Don Black recalled a joke in showbiz circles of the time: “Someone once said that the second world war must have been started by Vera Lynn’s agent.”

But how did it all start for Lynn? She grew up in Ladysmith Avenue, East Ham, east London. Her father was a plumber and her mother was a dressmaker who made “beautiful clothes for society people”. When Lynn was seven, her mother decided to put her on stage in the local working men’s clubs. “I used to go from place to place by tram. A shilling would take you all around London and the suburbs,” she said. “I didn’t love it at first. I was a bit shy and nervous. I gradually got used to it.”

She was a pupil at Central Park Road school at the time, but she never sang there. “They didn’t like my voice at school,” she remembered. And laughed.

Lynn has always taken her work seriously. I was talking to the magician Chris Woodward, the official historian of the London Palladium. “During the Blitz, when she was playing at the Palladium, Lynn was taken ill with appendicitis. But soon after, almost singing in the ambulance on the way back to the theatre, she carried on – because the show must go on.”

Just another war story? Well, perhaps. But it can’t be denied that the war played a huge part in her life – and the lives of the war generation. For her, it started when she would sing to people who were using London’s tube station platforms as air raid shelters, driving there in her little Austin Seven.

But it was Burma that made a big difference. She wore a uniform specially tailored for her by the theatrical costumier Morris Angel, complete with a slightly feminised officer-type cap, stood on the back of a Jeep and sang her heart out. No concert platform for her. Travelling in the Jeep with just a driver for company got her close to her “boys”, as she always called them and calls them still, even if the comparatively few survivors of the 14th Army, to give it its official name, are now old, old men.

One of them, Vic Nibbs, now a mere 92, told me he always regarded Lynn as “one of the veterans”. “It was marvellous seeing her,” he said. “Very few other performers wanted to go to Burma, but she came.”

Lynn said of Burma: “Singing in the jungle was very hot and very sticky, which was a bit hard going. I had a little piano, which they trudged around on the back of a lorry, hoping it would survive the journeys. It wasn’t surprising that when I started singing, the piano had suffered and was slightly out of tune. To see the boys as they were brought into the casualty tents was very emotional. It cheered the parents up when they heard that I had been there. They thought it couldn’t be so bad.”

Dame Vera Lynn at her home in Ditchling, East Sussex, on her 90th birthday. Photograph: Alamy

That is why, before she was confined to her chair in the East Sussex house, she was always feted so enthusiastically when she attended the annual rallies of the Burma Star Association and other veterans’ organisations.

The magician David Berglas said he had a particular reason to love her. “She was one of the few artists to do a show for Jewish refugee children, to bring them over before war broke out. She was singing with the Ambrose orchestra and took part in a charity show to raise funds to get them out of Germany. I thank her from the bottom of my heart – because I was one of those children.”

After the war, Lynn went on television. “That was quite strange at first. With a special makeup. You wouldn’t dare go out in the street wearing it. But you can’t beat a live audience. You react so much on an audience. I used to focus on people’s faces. I found it much easier than looking into an empty void on TV.”

She also revealed a new talent. She didn’t just sing; she danced. Squires said: “She was wonderful. Afterwards, she said: ‘We brought back tap, didn’t we?’”

Inevitably, as Digby the dog chewed on another biscuit, I wanted to talk about her family life. She and her late husband, Harry Lewis, were married for 57 years. By all accounts, as her agent, he did all her “dirty work” – making the deals that were all part of the Vera Lynn operation. Their daughter Virginia and her husband Tom share the East Sussex house. “She’s been a brilliant mother,” Virginia – known as Ginny – said. “She always made sure she was here for birthdays and Christmas.”

“She’ll always be Auntie Vera to us,” said her nieces, Roz and Christine, in unison. They are the daughters of Lynn’s brother Reg, who is now 102. They remember times in their childhood when they would stay with their aunt in her then home in Finchley, north London, and she used to bath them. “She would sing: ‘Dirty hands, dirty face … what a disgrace!’” said Roz. Christine recalls: “At our wedding, she almost took over. I think my mother was a bit put out by that.”

So what has really been Lynn’s success as an artist? Black, who knows a thing or two about singers, put it squarely. “She’s a national treasure. A most dignified lady. A class act. There were no frills. She sings songs the way they were written. No vocal acrobatics. She’s so good and people respect her. You just listen to the voice and you know why she is so respected.”

Michael Freedland presents Sweetheart of the United Kingdom on BBC Radio 2 on Sunday 19 March at 8pm. His autobiography, Confessions of a Serial Biographer, is published by Vallentine Mitchell

Born 20 March 1917, East Ham, London.

Career Began singing in public at seven, and was a popular radio performer by her early 20s. During the second world war, as Forces’ Sweetheart, performed for troops in Egypt, India and Burma.

Most famous songs We’ll Meet Again, and The White Cliffs of Dover.

UK No 1 My Son, My Son, 1954.

Other interests Charity work with ex-servicemen and disabled children.