That a band who celebrated their outsiderness, their remove from society, their us vs them mentality, would end up living out the rock star clichés of drunken car crashes and bitter court battles is not lost on Marr.
And in his new autobiography Set the Boy Free, he goes into all of those things in candid detail.
Unlike most celebrity books, however, there was no ghostwriter. Marr did the graft, locking himself away in his room for nine months to write it.
As a huge fan it's pleasing to say that it's really great. An easy, snappy read, full of insider information and new anecdotes for obsessive Smiths fans to, er, obsess over. It's also mostly upbeat, with the friendships and relationships within the band being highlighted.
Marr says, he wanted to set the record straight on what life was really like in The Smiths. Typically it's been presented as living in the rain.
"There's been quite a lot of people who have made quite a lot of money through a more dramatic and silly and negative narrative," Marr says, referring to past books by 'authorities' on the band.
"I'm not going to have my life story sullied by some bullshit agenda. I'll tell it really how it was."
One of his main motivations for writing it was, he says, to put the love back in the band. Something he felt, been stripped out over the years as people focused on the members fractious post-band lives.
"I've got no reason to write this other than that was my life and those times were actually fantastic. When we were in the studio recording Big Mouth Strikes Again say, or when we walked on stage for our very first show or when we were on Top of the Pops or when we saw our first fans or when we created a brand new song.... how anyone could think the atmosphere was rancorous and neurotic or negative or anything less than ecstatic? I mean really, if you think about it, that's kind of silly.
"However when the band came to an end and it was untenable I'll tell that like it was too. "
How was it, I ask?
"It was f ***ing heartbreaking."
The strain of managing a globally successful band had fallen on Marr's young shoulders for most of the band's life. He was only 23 when the band split, and all their legal arrangements were bound by handshakes and promises. With such ramshackle arrangements court was something of an inevitability. But before the lawyers get involved Marr tells the story of four young dreamers hustling to get their demo heard.
"I just wanted my mates to think it was as cool as any other modern band that was around," Marr says of the recording.
The book tells how he bowled up to Morrissey's front door to ask if he wanted to start a band, despite not knowing the bespectacled and slightly bemused fellow whose mother answered the door before calling him downstairs. The connection, he says, was instant.
"It was because our lives were wrapped up in our need to express ourselves and be in a band. The differences in our personalities were - and still are - really vast. But there was something inside of both of us that was really, really unique that we both shared.
"An absolute obsession, dedication and romanticism about pop culture, the need to be in a group, the need to write songs. It's fair to say an absolute desperation for all of those things came to fruition. When you find someone else who can help you be the lock or you be the key, whatever, then that's quite a rare and powerful thing."
But just before those reunion bells start ringing, Marr says, "but to put it bluntly I was always destined to play with lots of different people and I think Morrissey was always destined to be a solo guy.
"The fact of the matter is that it's amazing The Smiths stayed together for as long as we did because Morrissey and myself are so different. And I'm totally cool with that."
Marr seems like he would be totally cool about a lot of things. He's totally cool to talk to and his book is full of totally cool stories and photos of the young guitarist looking totally cool. There's no affectation, he's genuine, with an enthusiasm for music that obviously runs deep.
Indeed some of the most enjoyable passages in the book are his tales of how some of those Smiths classics like This Charming Man or How Soon Is Now came to be.
"One of the great things in doing the book was writing about those moments when inspiration struck. I made a conscious decision before I started writing that I wanted to describe those moments. Not just for other musicians but for people who want to hear about it, people who like the songs," he says.
"I tried to do it in such a way it didn't bog everybody down with boring technicalities. But at the same time I didn't want to underestimate the reader and figured that as long as I wrote it skilfully enough they would understand the process and might find it interesting."
What's clear is the respect Marr has for the power of music.
"I'm not sure that a song can change the world but I know a song can change a life," he says. "I know music can do that because it did it for me. And I've been very fortunate to do that for other people, which is something I don't take lightly. I've managed to hang onto that idealism because I know it to be true.
"A song could be poignant, get you out of bed in the morning, or as I talk about in the book, get you to school, get you through school. I've always kept that idealism and I'm glad that I've never become jaded by it."
Title: Set the Boy Free
Publisher: Penguin Random House
Price: $40
