Johnny Marr laughs. “The R-word? Do I mind people bringing it up? I’d better not mind, had I? Otherwise, my life would be intolerable.” If the Manchester air is rife with talk of reunions, the former Smiths guitarist is swift to put things in perspective. He says that in the 19 years since he walked out of the group — effectively splitting them — he hasn’t heard a Morrissey album all the way through: “I always think I’ll probably know what they’ll sound like — and when I get around to hearing them, I’m usually right.”

It doesn’t take much, however, to get the rumour mill grinding. In this case, it’s the news that at the end of this month he and the bassist Andy Rourke are set to appear on stage together for the first time in 19 years, along with several other Manc-pop luminaries, as part of Manchester v Cancer, a benefit concert to raise £1 million for alternatives to chemotherapy at the city’s pioneering Christie Hospital.

But even allowing for the fact that Morrissey is preparing for the release of his latest solo opus, is it really so fanciful to imagine someone picking up the blower and seeing what drummer Mike Joyce is up to? With vocalists from such fellow performers as New Order, Badly Drawn Boy, Elbow and Doves on hand, surely anything is possible on the night? “Now, just a minute,” cautions Marr. “Me and Andy — we haven’t even got as far as working out what we’re going to play together. And, as for Mike, that isn’t going to happen.

“Why not? Because the band split up! There was a court case! Get up to speed, for f***’s sake!”

“Sorry,” I stammer, “I just got a bit confused because . . .”

“F*** off! You’re not confused!” says Marr. He thinks I’m pretending to be a bit thick but I’m not pretending at all. And if I’m confused, it’s precisely because of that High Court case, in which Judge Weeks famously ruled against Morrissey and Marr, awarding Joyce £1 million over allegedly unpaid royalties (Rourke settled out of court). Given that the case was brought jointly by Rourke and Joyce, it’s surely a surprise to see Marr hanging out with any Smiths at all. “All right, I’ll let you off,” says the guitarist, squeezing his mint teabag against the side of his cup. “But Andy and I go way back before the Smiths. Our friendship was bigger than that.”

Marr’s profile may never match the days when he was a full-time Smith. Nonetheless he has the restless air of a man for whom retirement is not an option. He’s just back from Portland, Oregon, where he has been working with the established Seattle band Modest Mouse. His friendship with the Shameless writer Paul Abbot looks set to spawn an unlikely collaboration, a series of TV films based on the Pendle witch trials in the 17th century. Come summer, a new album with his own band the Healers might even teach a new generation of fans just what it was about Marr that exuded alpha-male qualities even in the distant glare of a cathode-ray tube.

Encouragingly, he says that his children — aged 11 and 14 — prefer his new songs over the stuff more commonly associated with their dad. “This Charming Man,” he suggests, “is probably a bit too quirky.”

No such obstacles, of course, for the “kids” of the 1980s, whose attics heave with Letrasetted videocassettes chronicling the Smiths’ imperial phase. It’s an albatross that Marr wears lightly. This year marks the 20th anniversary of The Queen is Dead, the album that, by Marr’s own admission, features some of the Smiths’ “best ensemble playing”. I ask him if — as rumour has it — there really is an unfaded eight-minute version of Morrissey’s apocalyptic address to the dwindling Empire. In fact, there’s an even longer one in existence: “Funny you should say that, because the record company want to put out some rarities, so we’ve spoken about the longer versions of The Queen is Dead: the eight-minute one and another one where we played for 12 minutes. It sounds like Can or something.”

Is that’s a good thing? Marr is a fan, although Angie, his wife of 20 years, doesn’t rate them. It’s good, I tell him, that he’s married to a woman who has an opinion about Can. “Well, she’s the reason why Hand in Glove sounds the way it does. We were visiting my parents and I was playing around on a crappy guitar that I’d left behind there. Then I got the idea for the riff, but because I had moved out, there was nothing to record it on, so Angie borrowed her parents’ Beetle and drove this live riff over to Morrissey’s house. On the way, she said, ‘Make it sound more like Iggy!’ And bang! Hand in Glove!”

“Wow. Sounds like you should form a band with her,” I suggest.

“Are you joking?” comes the reply, “Why do you think our marriage has lasted this long?”

Manchester v Cancer is at the MEN Arena on Jan 28. Tickets: 0870 1908000