THERE is music and there is friendship. In the story of The Go-Betweens both matter equally. It is still winter in Brisbane when I call Robert Forster. Eight in the evening. Earlier today he was out in his shed in the back garden writing and playing guitar. He is making his way towards another record, he says.

Right now, though, he is reminiscing about the band he once was in, about the friend he had in that band and the joy they found in the music. A joy cut short when his friend died.

It is difficult, now, to not add a freight of melancholy to the story of The Go-Betweens. Partly, because throughout the 1980s they were the almost men of indie pop, literate Australian outsiders much loved by critics and fans but never able to convert that adoration into a hit that could have made all the difference to their commercial standing.

But mostly because on May 6, 2006 Grant McLennan, Forster's friend and fellow songwriter went upstairs to lie down before hosting a housewarming party and never came down again. He was just 48 years old when he died of a heart attack.

Now Forster has revisited all those yesterdays in a new book, Grant & I. It's a beautifully written memoir that charts the history of the band and the history of the duo's friendship, from their meeting to the final day of McLennan's life.

For Forster it is far enough away from the pain of that day but close enough for the memories to be close and reachable.

"I just wanted to write down and celebrate what we did," he tells me, "because not a huge amount of people knew it.

"I thought there were things we did that deserve as much attention as I can throw on them; how good the group was; what our lives were like and what it's like for two teenage boys to start an artistic adventure and ride it out for quite a long time."

Forster and McLennan met at university in the mid-seventies. Music wasn't the glue of the friendship. Indeed, initially McLennan, a huge film fan, wanted to direct or become a film reviewer. "He burnt for the screen," Forster writes in Grant & I.

But Forster was already in a band and asked McLennan to join. Eventually he did. The result was a band fronted by two songwriters of equal merit. That was the strength of The Go-Betweens but also, perhaps, a drawback.

"It was very hard to – I think it always is – to sell a group with two songwriters on guitars," Forster concedes. "The big exception is the Beatles, but it's really hard to think of many other groups besides that where you don't have someone roaming the front of the stage with a microphone."

Still, almost from the off the band's song catalogue was full of heat and light and novelistic intensity. "That striped sunlight sound," they labelled it themselves. They travelled back and forth between London and Australia (with even a visit to Glasgow in the early days of Postcard) trying to gain the necessary traction.

Along the way the band's interpersonal relationships deepened and grew more complex. Forster started a relationship with Lindy Morrison, who would become the band's drummer. Later McLennan would fall in love with Amanda Brown, a classically trained violinist whose involvement with the band coincided with the closest they ever came to chart success on tracks like Streets of Your Town and Was There Anything I Could Do? at the end of the 1980s.

The question, I guess, is did things ever threaten to go full-on Fleetwood Mac, Robert?

"Well, no, because it came so gradually in a way. Lindy and I broken up and then Grant and Amanda started."

Presumably romantic involvement changes the band dynamic though. "It does, but not as much as you'd think. The band quickly ends if a couple tries to power over everyone else. I think couples know that in bands that they have to be careful. That probably happened in Fleetwood Mac. That probably happened in Abba too. They probably treaded fairly carefully whereas it can look from the outside as if it's a melodrama.

"Five guys in a band can get up to more trouble than a band with two couples. That's a certainty."

The later story of the band is break ups and make ups and debt. (The band received no royalties outside Australia for 26 years after they split at the end of the 1980s.) When McLennan announced he was going solo it ended his relationship with Brown. The two songwriters teamed up, made solo records, and eventually relaunched the band at the start of the new century

Indeed the band were going strong again, two albums to the good, in 2006 when McLennan died. But reading Grant & I it's hard to come away with anything other than the perception of McLennan was something of a lost boy by that point.

"Yeah he was, he was," Forster agrees. "He was in a shared house. Basically at the end of his life he was living the way that I knew him right at the start when he was 17 or 18.

"That's great when you're 17 or 18 drinking and partying and carrying on and being in a band and being on the road and in studios. All of that is great up to your mid-thirties and then it can't go on. You've got to change your habits you've got to change the spectrum of your life."

Forster did. He got married, even moved to Germany for a while. And then he was diagnosed with Hepatitis C. (Thankfully, all is good at the moment on that front). For McLennan, however, change proved harder.

"He was unhappy because I think he knew that things in his life weren't were they should be for someone of his age and time so I think that just made him drink even more and, yeah, I think time totally caught up with him."

Maybe things were changing. A new home, a new partner. But time caught up with him in his bedroom in 2006.

What remains? Memories and songs that now seem all the more burnished in retrospect (their 1983 non-hit Cattle and Cane is one of the most literate and aching examples of Australian songcraft in the canon, a Tim Winton novel squeezed into three minutes).

"We weren't travelling the world playing to 15,000 people a night and having hit singles," Forster says. "We were really working on our song-craft. We were putting everything we had into our music. if you do that there's always a chance that what you do – no matter in what field – it has the chance of lasting."

In Brisbane there's even a bridge named after the band now. More than 10 years after McLennan's death the legacy of the band is written into the city. There's a documentary film coming soon too.

And as for the friendship? How often, Robert, is Grant in your head? "All the time, all the time. I just think he will always be someone to the end of my life who will be bubbling and moving around. He'll always be there but it doesn't feel overwhelming. it feels in a good way.

"I've come to peace with his passing and he remains a lasting influence on me. That's the best thing I can say."

It is more than enough.

Grant & I, by Robert Forster, is published by Omnibus Press, priced £16.99. Forster will be talking about the book and playing a live set at Mono, in Glasgow on Thursday September 7 at 7.30pm.