Johnny Marr has to put off our phone call this morning. The perils of jetlag don't discriminate – indie rock royalty or not – and when you need to take a nap that's the end of the matter, there's no fighting it. Marr and his band are freshly back home from a sizeable US adventure, taking in 17 shows ('actually a fairly short run for us,' he offers), returning to the UK to immediately open for the Strokes at Hyde Park and then travel to play a festival in Newcastle. 'My body is somewhere over the Atlantic,' he yawns, before sleepily confusing the metaphor; 'and my body is somewhere over … Edinburgh.' We can forgive him some well-earned shut eye. He probably still needs a bit more.

The Smiths ostensibly ended when Marr, one of the most innovative guitarists of his generation, quit the band in June 1987. He was 23 years old then, with a back catalogue most musicians could only dream of in the bag, the fruits of a magical songwriting partnership up there with the greatest. It would have been easy for Marr to bask in that glory and take early retirement – creatively speaking – but not possible for a man who loves his craft. A quarter of a century on, after stints with the The, the Cribs and Modest Mouse, he's wholly invested in a solo career that sees him graft as hard as ever, and he's not complaining about it for a second. 'When I was a kid,' he says, 'even the more challenging stories of the life of a musician sounded great to me. Which is pretty handy – when those things happen, you know you've signed up for it.'

The touring is a knock-on effect from the success of Call The Comet, Marr's 2018 album which imagined a better alternative universe as a response to the annus horribilis that was 2016. The approach was a peaceful one and the output meditative, rather than furious and explicit (unlike a certain someone).

'The impulse for Call The Comet was all about escape from the political dialogue', he tells me, calling his creation a 'sideways version of sci-fi' that happened by accident. He adds, wryly, 'I wanted to avoid mentioning names and politics directly, which I felt would have just been crass. Once I had "Rise", "New Dominions", and "The Tracers" I identified that was what I was doing, and re-read HG Wells, JG Ballard, EM Forster … that's one of the great things about doing art. You stumble upon things during the process.'

Science fiction influences aside, the writing process for Call The Comet offered Marr the chance to do things in a different way, one which he embraced, which in return led to his most accomplished collection to date as a solo artist. 'I didn't go in the way I usually go in to make a record, prepping the band and getting the demos together. I just went into this big space on the top floor of a factory on the outskirts of town, mostly on my own, and started plugging guitars into machines, drum machines into guitar effects, as a kind of experiment and form of expression'.

Unsurprisingly, Marr was particularly horrified by the Manchester bombings, channelling that into the album's highlight and closing track, 'A Different Gun'. That creative process is something he found very cathartic, adding: 'I feel very fortunate not only to have that aspect of my life, but that it happens to be my career as well. That's something I'd be doing if I was successful or not, I think. That creative necessity's been with me since I was a little kid.'

Johnny Marr plays Edinburgh Summer Sessions with Primal Scream, Princes Street Gardens, 10 Aug, 6pm, £50.65–£75.90.