HUNTER DAVIES emails directions to his north-west London home: after exiting Tufnell Park tube station and climbing a hill, I am to “look out for Julian Barnes hanging about”. The lesser-spotted Booker prizewinner is only the start of a trip into celebrity culture. I am to note on the right, the home of Ed Miliband – the house number is divulged. “Opposite Benedict Cumberbatch is moving in.”

It’s like a Kentish Town version of one of those Hollywood Homes of the Stars tours. It doesn’t stop there. During the course of the interview about his latest memoir, A Life in the Day, the Beatles biographer, ghost-writer of Paul Gascoigne’s mega-selling autobiography, Gazza, author of 97 books (it may be 98 by now since he is prodigiously prolific), unrepentant party animal and gleeful gossip asks me if I’ve heard of his neighbour, one Sue Perkins.

The comedian, broadcaster, writer and actor lives three doors down. Clearly, she hasn’t made enough dough from the Great British Bake Off because Davies whispers confidentially: “She can’t afford a whole house – only two-thirds of one!”

A working-class lad, born in Johnstone, Renfrewshire, the 81-year-old grew up in Carlisle. His last memoir, The Co-op’s Got Bananas! (2015) breezily recalls the poverty of his upbringing in a chilly, cheerless council flat in post-war Cumberland as well as the love story between him and his beloved late wife of 56 years, the celebrated novelist and award-winning biographer Margaret Forster, who died of cancer at the age of 77 on February 8, 2016.

He is proud of the fact that he and Margaret – “the cleverest woman in England ... perhaps I shouldn’t say that but it’s true. She was a real writer; I’m just a hack” – paid only £5,000 for their enviable Victorian villa some 50 years ago. When he tells people this, it makes them sick, he chortles. It must be worth more than £3 million now and it’s not the only property he owns, but as Davies points out, “Margaret hated me talking about how much money we had made”.

Which is rich since one of the three columns he still writes is for the Sunday Times Business and Money section. “I’m awfully well-off but mean with money – it’s my pure Scottish blood.” He’s certainly thrifty, a firm believer in recycling – especially his own words. Some anecdotes in A Life in the Day, which takes its title from the much-emulated Sunday Times colour magazine column which he launched in 1975 and is perhaps the longest running column in the world, has appeared elsewhere in the avalanche of articles and books he’s forever writing about his life, his family, his Lake District and his many obsessions, ranging from football to collecting prime ministers' autographs, Suffragette memorabilia and, inevitably, stamps.

If ever a man wore a metaphorical anorak – he’s actually sporting It Ain’t Half Hot Mum baggy shorts, as he was the last time I interviewed him at the then family home in the Lake District – it’s Hunter Davies.

He’s also famous for recycling gossipy stories about everyone from Paul McCartney to Wayne Rooney – he even recycled the A Life in a Day idea. He came up with it while editing Palatinate, the student newspaper at Durham University. And, he notes over coffee which he gives me in Margaret’s favourite cup, his new book is actually A Life in the Day, Part 2. There’s a Part 1 somewhere on those groaning bookshelves where his oeuvre is stored.

There is, poignantly, much that is new and desperately moving in the memoir, however, particularly about Margaret’s final, pain-wracked years and her death in Hampstead’s Marie Curie Hospice. He has written endlessly in the past about their enduring marriage. They met as teenagers. Academically brilliant, Margaret was the first pupil from Carlisle and County High School for Girls to win an open scholarship to both Oxford and Cambridge.

They went on their first date the day she finished her A-levels. They were a couple from that moment until Margaret died more than 40 years after first being diagnosed with breast cancer and undergoing a double mastectomy. “She was a fatalist. She always knew the cancer would return; I was in denial,” he says.

In the closing chapters of his memoir he writes of the quiet courage, grace and dignity with which his wife faced the cruel disease when it returned nine years ago. He had never written about her illness since she insisted on keeping it secret for many years, even from their daughters Caitlin and Flora, son Jake and four grandchildren, all of whom live close by.

Davies says Margaret is still with him and will always be with him. Even when I try to talk to him about his memoir, which is subtitled Memories of Sixties London, Lot of Writing, the Beatles and My Beloved Wife, all he wants to discuss is Margaret’s forthcoming book, The Diary of An Unknown Schoolgirl. The title is a nod to Margaret’s 2003 The Diary of An Unknown Woman. (In any case, he admits that he never reads his own books – he’s too busy writing the next one and is aiming for 100 not out.)

“Have you ever been up to Margaret’s study?” he asks, trotting upstairs to the small room at the back of the house where she wrote her 26 novels, such as Have the Men Had Enough?, as well as superb biographies of other writers – Elizabeth Barrett Browning and Daphne du Maurier, for instance. I have never been in this room. Margaret was intensely private – an introvert to his extrovert – although I interviewed her several times, despite her dislike of the publicity machine. Davies once smuggled me in to her Loweswater study, however. “Don’t tell her,” he warned. “She’d kill me.”

In her London room, there is clutter of papers and books from her Lake District office. He sold the beautiful Victorian house, where they spent every summer for more than 30 years, to a millionaire. In his own, much larger study he has a stack of Margaret’s diaries, discovered after her death. He reckons there are a million words at least, written in her bold, immaculate, fountain-pen handwriting – she wrote everything by hand.

The 10 diaries were a revelation – he found them shortly after Christmas when he started to clear her room. “To my amazement, I found one million words, unpublished, which I had never read. We all knew she kept five-year diaries, each with 365 pages – ‘a little amusement’ that began in 1973 with our youngest Flora’s birth. She always said they were purely domestic but she fibbed. There’s a lot about the children and our domestic lives but there’s a surprising amount about her own life and feelings and a great deal about her cancer, which she never talked about.”

Also, he discovered three smaller, slimmer diaries that he never knew existed. They are her schoolgirl diaries – one from 1949 when she was 10 and about to sit the 11-plus, one from 1952 aged 14, another from 1954 aged 16. Her publishers, Chatto & Windus, so loved the 1954 diary that it’s coming out this Christmas. “It’s part social history, with events of the day mixed up with her life at the high school. It’s typical Margaret, outspoken, opinionated and clever.

“She lists all the books she read in 1952 – 136. In 1954 she read 66 – that was her O-levels year. She gives each book a personal rating and the same for films she saw and radio plays she listened to – though she often never heard the endings as her dad would come home from the pub and insist, ‘Switch that bloody thing off!’

“Reading the diaries made me laugh and made me cry. They made me realise what good times we had, many of them I’d forgotten,” he says, showing me a proof of the dust-jacket for The Diary of An Unknown Schoolgirl and reading aloud some of her trenchant words.

Margaret’s final words to Davies as he sat by her bed in the hospice telling her he didn’t know how he would manage without her, were: “You’ll be fine.” Is he? “I keep busy.” He writes his columns, lunches with old friends, goes to every event he’s ever invited to and never has to worry about cooking since “the food fairies” – his family, neighbours, female friends – keep the fridge stocked up with tasty stews and quiches.

After I interview Davies, I exchange emails with his daughter Caitlin, also a fine writer. I tell her her dad seems in fine fettle. She replies, “Yes, he is in fine (ish) fettle and it is better that he is running around as usual rather than sitting at home and moping.”

Being in fine (ish) fettle, as anyone who has lost the love of their life knows, is quite an achievement.

A Life in the Day: Memories of Sixties London, Lots of Writing, the Beatles and My Beloved Wife, by Hunter Davies (Simon & Schuster, £16.99)