When I was a very young journalist I was sent to interview Kevin Ayers, the singer of Soft Machine who’d thrown off fame and was now living, aged 61, as a recluse in the south of France.

The thinking was that a middle-aged man interviewing Ayers would be caught up in his legend as the rogue cherub of psychedelic whimsy, a serial shagger and absurdist whose songs had titles like “Whatevershebringswesing” and “Oleh Oleh Bandu Bandong”. My colleagues pictured Ayers trout fishing in Carcassone and drinking claret. But I found him, in his sleepy walled village, blinking under the rim of a fisherman’s hat, clutching a blue plastic bag filled with pills and wincing from four broken ribs. He drank two bottles of wine during our first conversation, unable to make eye contact, then drove me down a mountain and downed a pint of Pernod in a bar, asking to sit in the shadows.

He was achingly honest. There was “no such thing” as the prog rock Canterbury scene, he shrugged: “There were no more than half a dozen people doing what we were doing – in a cathedral city that had its quota of real wankers.” He expected me to spend the night with him after our interview, until his manager explained it was no longer 1967. I got on the plane the next day so heavy with the burden of writing a true picture of his life that I cried all the way home.

He died a while later, leaving his daughter, Galen, in charge of his estate, music and unpaid tax bills. “When you met him, what state was he in?” she asks, down the line from LA. Galen, a musician herself, is the child of Ayers’s relationship with Kristen Tomassi, the first wife of Richard Branson – who lost her to Ayers at a wife-swapping party on a houseboat in Little Venice. Galen spent her childhood near the Majorca hippie idyll of Deia, where Ayers would come and get her every weekend “if he didn’t have a hangover”, take her fishing and cook with her, and teach her how to put make-up on (“he had much more than my mum”). She has spent much of her adult life trying to reconcile her love for her “best friend, brother, son, father, god” with the “complete fucking mess” he left behind.

She reminds me of Kevin when she talks about the absurdity of leaf-blowers for part of our interview. Ayers described his Deia period as his “golden years”. The only thing he ever gave his daughter was his J-200 Gibson, passed on to him by Jimi Hendrix, which he pushed across the floor on her 21st birthday. Galen talks about him in the present tense and describes him as animalistic: “Some people are quite built up. Kevin is like a raw nerve. Like a little animal.” They had an “enmeshed” relationship – in adult life she “became his caretaker for a good ten, fifteen years. He never stopped being a god to me – but it became too painful to look at, for a minute. And I knew that if I looked away, he would go, hey, I’m going to die then! And he did.”

Next to the bed where he died was a plastic Marks & Spencer’s bag of photos, many of Galen with Kevin, sitting on his shoulders or playing with the top of a champagne bottle. She’s spent seven months putting them together in an unusual book, Shooting at the Moon: The Collected Lyrics of Kevin Ayers, alongside his verses and recipes: “No matter what happened in his life, he always had that stupid plastic bag of photos,” she says. It moved between “every single shitty house” he lived in.

It’s not the same as talking to other rock star kids. Galen was kept out of the limelight because Ayers wasn’t really in it himself. “He had a childlike brain and didn’t want to have to engage,” she says. “He was always smiling enough, lovely enough and good-looking enough to enlist some pawn instead – every other week he’d convince some young girl to clean his house for no money.”

I tell her that I found interviewing her father strangely upsetting and she says, “then we are the same. I have felt like this every day of my life. How do you protect him, how do you keep him alive while staying true to yourself?”

Working through his legacy – 350 songs – allows her to “individuate”. “I feel like a good girl. This book can speak for him – I’m not the only one that has to carry this wonderful, colourful human around.”