It takes Joanna Trollope weeks to find an interview time that suits us both, but that’s the point of her new book City Of Friends – as busy working women we’ve got a lot to fit in.

Children, marriage, parents, jobs, childcare, relatives, domestic lives, households to run and of course work.

“Exactly,” she laughs, “What spurred me on was that there were no books about women and work. Books always seem to be about their romances, and of course women do define themselves through their relationships, perhaps more so than men. Yet so many of us go to work and are defined by that. I thought it was about time I tackled it.”

So in true Trollope style, she headed down to Canary Wharf to find some suitable candidates to interview. “It was very interesting because the City is still a bastion of male employment, but the women there were very open, except to the media, who still define them by their shoes or hair, almost as sex objects, which is so horrifyingly old fashioned,” Joanna says shaking her head in exasperation.

“But nothing surprises me anymore, not even the letters from people telling me they can’t understand why anyone would buy my books.

“I always write back of course, thanking them for being so candid. Well it’s only polite after they’ve spent all that time letting me know how they feel. You can’t ignore people.”

Joanna talks as she writes, making for a captivating interview – being dynamic, insightful, wise, interesting and clued up, while never relying on ageist clichés about how she should feel or view life, and an endless people watcher.

“I could quite happily sit in a departure lounge from now until the end of time,” she tells me, “because people are so delightfully unguarded. It’s the same on public transport. I think I just file it all away into a subconscious department in my mind, ready for when I need it. But I do think I know human nature. I’m very rarely wrong at this advanced stage in life,” the 73 year-old chuckles, “which means I shall never run out of ideas.”

Her current book City Of Friends is Trollope’s 20th novel and as ‘intensely topical’ as ever. It depicts four friends who leave university to become highflyers.

Did Joanna delve into her Oxford memories to embellish the novel? “I was at St Hugh’s 100 years ago when there were seven men for each girl and endless chaps who’d got in just because they were good oarsmen – that sort of division.

“There were five all-girls colleges, and men had to be out by 10pm. Actually it was quite relaxing and peaceful, lots of girls wandering around the corridors with wet hair and towels on.

“And I made some amazing friends.” Are they still friends? “Two of them died of cancer, one 20 years ago, one 10,” she says sadly. “But they taught me a lot about friendship and how valuable it is.”

So what’s the answer then? Are we making progress? “My mother was born in 1919 the year women got the controlled vote so there has been significant progress made in the last 100 years but there is still an enormous transition to be made which is ongoing and will be for generations.

“Of course there will be readers who think ‘what’s the point’ when they read City Of Friends or think that it sounds like an absolutely awful way to live. It won’t suit them all, but for an enormous number of people it will ring true - although it’s not a question of creating characters I like, it’s about the readers believing in them and the reality I’m trying to create.”

“Because working is like cramming quarts into a pint jar - some days it works and others it doesn’t, but we will get there.”

Did Joanna know she wanted to be a writer (she is distantly related to the Victorian novelist Antony Trollope) when at Oxford? “No, I wrote my first novel at school about the kind of teenager I wished I was, rather than being bespectacled and geeky, which my daughters think is hilarious. I didn’t write my first proper novel until I was pregnant with my first child aged 23/24.”

It’s hard to imagine this thin, elegant, sophisticated lady as an awkward, introverted adolescent. “I was very ordinary with specs and braces. And when I was at Oxford I was similarly swotty and conscientious, like the sixth former I’d been. My essays were always on time and I never missed a tutorial,” she said rather regretfully.

“I didn’t feel academic at all. Put it this way – everyone at my grammar school in Surrey had a day off when I got into Oxford.

“But I remember overhearing my mother talking to my aunt after I left my first husband saying: ‘I don’t know what’s happened to Joanna. We never had any trouble with her until she was 27’, so perhaps I’ve done my rebelling later in life,” she smiles, with a hint of pride.

Having already written the next novel about the effect on families of late-in-life-marriages, Joanna then announces she’s taking a year off. “There won’t be a book in 2019 but there will be in 2020,” she says firmly.

What will she do? Head off to a desert island? “Ha Ha. Not a hope,” she laughs. “Just catching up with stuff, charities, family – I do a lot of work with The National Literacy Trust because of the disgraceful literacy rates in this country. I don’t have a very big profile but what I do have I might as well use.

One of her daughters lives in Oxford so Joanna is a regular visitor and has “a real affection for the Oxford Times”.

But back to her year off! “Oh come on. I wouldn’t be very good on a desert island. I wouldn’t be able to study anybody. Perhaps I’d study the animals instead?” And become the next David Attenborough? Another shout of laughter. “Well I’m the right age.”

Has she had enough of writing then? “It’s not just about time. I don’t think I could teach creative writing anyway because although I could show people how to structure a novel, I cannot teach them about having the X Factor – What gives someone their compelling voice?” If she doesn’t know, no one does.