Who are our parents, really? It’s a question few of us consider until later in our lives, if at all. It wasn’t until the death of Ben Watt’s father in 2006 that the musician and writer became compelled to examine his parents’ lives in depth.

Of course he knew the stories – that his mother had been a Rada-trained actress who’d shelved her career to have children; had met his father, a Glaswegian jazz musician, when both were married to other people. He knew there had been a long affair before they finally divorced to be together, and he had personally lived through their often tempestuous relationship.

But until he came to write Romany And Tom, his portrait of their lives together, these details were just “bullet points” on a timeline.

“In writing the book I suddenly became aware of the human scale of their lives.

It made me realise these heroic figures who dominated so much of my life were exactly the same as me, battling the same issues and problems that we all do.”

Throughout his childhood it had never occurred to him that his parents were ordinary, flawed humans. “I felt I was in the presence of two huge characters,” he says. As with many of us, it was only when his father became ill – and child became carer – that he started to see them as mortals. Then, after his father’s funeral and with his mother in the early stages of dementia, he found himself holding a sealed envelope containing notes and letters documenting the story of their relationship.

Writing the book became not a choice but a compulsion, says Watt, now 51. “It was something that was coming down the track towards me.”He needed to work out who these people were and used to be.

Best known for music – with wife Tracey Thorn he makes up the pop duo Everything But The Girl – Watt’s first forays into writing had come about in a similarly urgent manner. In 1996, he wrote Patient, which documented his battle with Churg- Strauss syndrome, an autoimmune disease that often proves fatal.

There was a sense with both titles that “if I could name it, I could tame it”.

In the process of writing Romany And Tom, he discovered as much about himself as about his parents.

The only child of their marriage (although he has four half-siblings) he realised he had often sided with his charismatic father, and characterised his mother as crotchety and irritable. As the book unfolds, the author’s allegiances change; “I developed a huge amount of sympathy for her and what she put up with from my dad and it’s improved my relationship with my mum as a result.”

Watt’s father Tommy had become very successful in the late 50s, leading the Centre 42 big band and winning an Ivor Novello award. But it was short-lived and when rock ’n’ roll took over from jazz, Tommy refused to embrace this new music and his career plummeted as a result.

Still, it had not occurred to Watt how conflicted his father must have been when his son carved a lasting success out of the music he had shunned.

“On the one hand he was very proud I’d become a musician which was the job he thought any right-thinking person would want, but coming to the Royal Albert Hall to see me do a sell-out show must have been difficult for him.”

After giving up acting for motherhood, his mum later made a career as a successful journalist and broadcaster but her fortunes faded too and in Watt’s memory his parents’ later years were marked by arguments, apologies made by memo, and the consumption of brandy “not poured as a shot or even a double, but like full glasses of water”.

In contrast, Watt’s marriage to Thorn appears to be characterised by a respect and solidarity that after 30-odd years of living and working together, not to mention three kids, makes the couple something of a curiosity. They work at it, explains Watt.

“I was very aware of the tempestuousness of my parents’ relationship and it’s something we try very hard not to let creep into ours.” It helps that they are adept at each doing their own things together. He recounts the story of their first date as teenagers at Hull University when, unable to agree on a film to watch, they went into separate screenings.

“We met up for a pizza afterwards and had a lot to talk about and were both happy. I think that’s quite an accurate thumbnail sketch for what we’ve done the rest of our lives.”

Outside of their joint work, Thorn too has had success as an author with Bedsit Disco Queen, her memoir of a life in pop music bound up, of course, with her life with Watt. Has he ever felt uncomfortable with all the exposure – his family, medical history and marriage laid bare?

“I’m not sure I understand the word ‘exposed’,” he says.

“I think transparency is often the key to good relationships.

If you’re open with people I think you get on better with them. But perhaps that’s a reaction against my parents, where so much was left unsaid.”

The desire to connect – with audiences as with readers – is what drives a performer on, he adds.

“It’s what makes me want to be reflective and open and say things that are true.”

It’s no coincidence that Watt has recently released Hendra, his first solo album since 1983. It’s been a period of intense reflection and thoughts of his solo career, abandoned when he met Thorn and formed Everything But The Girl, had been preying on his mind. “I threw my lot in with Tracey for so many years and I’ve always wondered what would have happened if I hadn’t.”

When his half-sister Jenny – the family peacemaker and one of the book’s great champions – died suddenly and unexpectedly in 2012, it was the trigger for Watt to return to the studio alone.

“I realised I had a lot of things I wanted to say that were connected to the book and connected to her, specifically how we deal with crises in our life as we get older. That became the driving force behind the record. All the protagonists in the songs are at breaking point in some way and that’s the through line really, how we cope in a crisis.”

lBen Watt will discuss Romany And Tom at a Brighton Festival event in the Brighton Dome Studio Theatre on Wednesday at 8pm. Call 01273 709709.

He is also at Charleston Festival on May 22 Romany And Tom is out now (Bloomsbury, £14.99)