A few weeks ago Ben Watt presented an advance copy of his new book Romany And Tom, to his elderly mother. As a former showbiz journalist who’d once attempted to write an autobiography of her own, she was thrilled to see that her youngest child had published a memoir of her marriage to her late husband, Scottish jazz maestro Tommy Watt.

Not that Romany was able to read much more than the title. Within minutes of Ben showing it to her, she’d forgotten all about it. Suffering from dementia, she resides fulltime in a UK care home.

“Everything is new to her every ten minutes,” the 51-year-old author, DJ and musician explains, speaking in a soft London accent. “So you can get her attention and show her the book and she can respond and be reactive and you can get her to focus on it for a short period of time. But bring it up ten minutes later and it’s brand new to her again.”

In Dublin for two days of promo, Ben has a far heavier schedule than most authors – press, radio and TV. Internationally famous as one half of successful ‘90s alt-pop duo Everything But The Girl (with wife Tracey Thorn), he’s taking it all in his media savvy stride.

Holding court in the bar of Brooks Hotel, he suggests Hot Press sit beside, rather than opposite, him and helpfully places the digital recorder on the armrest of his chair. He’s a friendly type, if a little guarded. But then, all recently published memoirists are guarded.

Ben has written one previous book. 1996’s harrowing and humorous Patient detailed his year-long battle with Churg-Strauss syndrome, a rare autoimmune disease that often proves fatal. Not to be outdone, Thorn published her autobiography, Bedsit Disco Queen, last year.

“I remember when I wrote Patient, Tracey was kind of, ‘Wow, a book! That’s really grown up. That’s really kind of proper stuff ’. And I don’t think she had any plans to write anything at that point, but then, um, it just comes out.” He shrugs and laughs. “I don’t know… it’s something to do, isn’t it?”

When his alcoholic father passed away in 2006, Ben put his feelings down on paper.

“I wrote in a blur, just a rush of stuff. Not much, about 10,000 words.”

He put the pages away in a drawer and didn’t return to them again until almost six years later.

“At the beginning of 2012, I literally woke up as if from a dream - I don’t know how the idea was in my head - but I woke up and I just saw the end of the book. Mapped out.”

Romany And Tom opens with the titular pair’s health and relationship already in serious decline, both of them drowning the pain of their unhappy marriage with constant “large tumblers of brandy, not poured as a shot or even a double, but like full glasses of water.”

They didn’t start out like that. Tommy Watt was a working-class Glaswegian jazz musician whose 1950s heyday took him into the glittering heart of London’s West End – at the height of his fame, he won an Ivor Novello award. Romany Bain was a RADA-trained Shakespearian, who had triplets in her first marriage before becoming a leading showbiz feature writer. Divorcees from very different backgrounds, they scandalously came together like colliding juggernauts in 1957.

“I had this idea of only revealing what actually happened between them at the very end,” says Ben. “And this idea that you think you’ve nailed them as characters up until that point. Your allegiances shift and change. You think you’ve got them down, and suddenly this huge moment that actually defines them, in many ways was their relationship, hits you at the very end.

“As an idea, I thought that was strong and that’s what really got me going. I wrote it almost continuously for about nine months. Just wrote it. January to August, sort of time.”

Despite Romany’s deepening dementia, he didn’t feel any qualms about telling her story. He knew it’s what she would want.

“Well, she made no bones about writing very open stories about her family,” he says. “She wrote very famously about her own mother. She wrote a long article for Woman magazine in the mid‘70s when her mother died, which was widely praised by a lot of her peers for being a very open, forthright, unsentimental look at her own mother.

“So I think she saw the value in transparency. In just getting it off your chest and knowing where you all stand, and actually, you grow stronger through that.”

Although often an emotional read, it’s not misery lit. Growing up with his four older half-siblings, Ben had a reasonably happy childhood though later suffered from depression.

“I outline the tricky stuff about my upbringing,” he admits, “but I’m also at pains to point out there were good times with my parents. They were funny people, and you know, going to the football with my dad, his sense of humour; the fact that through it all they stuck together, they didn’t split up, they stuck it out. I think you put stock by that as kids; it seems sort of solid in a way. I mean, I was aware that it was tricky, especially in my teens it got bad…”

Once a major star of the British jazz scene, Tommy Watt fell out of fashion when rock ‘n’ roll took over the airwaves. Two decades after appearing on the cover of Melody Maker, he was working as a painter and decorator.

“Things got worse for my dad when I was six, seven, eight, you know, impressionable years. He was still possibly on the edge of a revival in a jazz career and he hadn’t quite had to accept that it was over. And then he had two or three years when he was great company, when he was just a decorator.

“Life was a lot simpler, he wasn’t drinking as much. It got harder in my late teens and early twenties when I think the realisation that it was over hit him quite hard and he was difficult to live with - I know my mum found him very difficult. But by that time, you’re kinda grown up and you’ve almost become the person you wanna be by that point.”

Ben has three children with Tracey Thorn. How will he feel if one of them grows up to write a memoir of their marriage?

“I think it’s possible that one of our kids might write about us one day,” he smiles. “I wouldn’t put it past them. We’ve got twin 16-year-old girls and Blake’s 13 tomorrow actually. But then, you know, a lot of our story has been told. At least half of our career has been part of that well-documented generation I talk about in the preface, whereas my parents were part of that slightly hidden generation.”

Even so, he’s probably not going to make it easy for them.

“Well, I was thinking to myself that, after this was published, I ought to go down into my garage and burn everything,” he laughs.

Romany And Tom is published by Bloomsbury.