THE perfect performance in the perfect setting,” one critic enthused about The Waterboys’ recent appearance at Glastonbury, and so it was. Over the course of an hour, lead singer Mike Scott and the latest version of his band ran through some of his best-known songs – The Whole Of The Moon, Fisherman’s Blues – as well as selections from the two most recent albums.

The BBC’s coverage of the set (still available online) wasn’t simply a foretaste of The Waterboys’ headlining performance at Wickerman this Friday; it also reminded us of Scott’s status as a highly literate songwriter who has habitually followed his musical instincts, changing his sound from album to album.

“I follow the music where it takes me, and the music tells me what to do,” Scott said in an interview earlier this year on French TV. “And if the music is telling me, ‘go acoustic’, ‘learn country music’ … that’s what I’ll damn well do.”

The 1980s were a case in point, when the distinctive, majestic Waterboys sound of such critically well-received albums as A Pagan Place (1984) and This Is The Sea (1985) gave way, in 1988, to a more traditional sound – rousing, beguiling – of Fisherman’s Blues, which was recorded in a prolonged, fruitful “bohemian adventure” in Ireland.

Edinburgh-born Scott had relocated to Ireland as part of his restless drive to create what he would describe, in that same French interview, as an “ever-changing, mercurial, organic music”. It became the band’s biggest-selling album, and he still regards the songs on Fisherman’s Blues as some of the best music he has ever made.

The last few years have also been instructive, with the 2011 release of An Appointment With Mr Yeats, with Scott adapting WB’s poems for song, being followed, after a four-year gap, by the southern soul swagger of Modern Blues, which was recorded in Nashville.

Home for 56-year-old Scott is Dublin, a city that seems to have got under his skin. “[It’s] a creative city, and I like that,” he says. “It’s good for my songwriting. After I left Dublin the first time, in 1991, after six years there, I always wanted to return. I finally got back in 2008 and have now lived there longer than the first time. I also like the size of the city – not too small, not too big – and that lots of people know me, but they don’t impose on me.”

The imagination in Dublin, he affirms, “is different from the British imagination. The Irish have a different consciousness, a little looser, freer in certain respects to do with storytelling and the creative arts – though less free in others, such as morality and religion”.

If you follow Scott on Twitter you’ll know that from time to time he tweets entertainingly about his life in Dublin. The week before last, he wrote about “several types of hell colliding” as the taxi in which he was travelling inflicted a local radio station’s Celebrity Spy programme on him; last weekend, he wrote about wearing a jacket so sharp that he was tempted to walk into tailors’ shops just “to freak them out”.

He’s active on Twitter, having posted some 31,700 tweets since February 2009. What are the advantages of maintaining such a presence? Has he ever had any negative experiences, or been trolled?

“The only thing I ever dislike about Twitter is getting pulled into fights with right-wing lunatics or other internet abusers,” he says. “I give as good as I get – I’m fond of telling right-wing fundamentalists that they need urgent psychiatric treatment, which indeed they do – but it gets boring very, very quickly.”

He’s effusive on the subject of Steve Wickham, the charismatic Irish fiddler who is his musical soulmate, and whose work has long been a key part of the band’s sound. Apart from a decade-long separation that ended in 2000, Scott and Wickham have played together since 1985.

“My musical relationship with Steve is the deepest and easiest musical relationship I’ve ever had. We’re attuned to the same wavelength and play like brothers – always have, since the first day he sat in my London flat and strummed guitars together 30 years ago.

“Since then, the connection has developed, of course, and broadened through many different styles, but the kernel is still the same. If one of us is playing, the other knows how to accompany it, intuitively, without any thought.”

One of Scott’s biggest recent projects was the Fisherman’s Blues six-CD box set, which details the fantastic amount of work that went into that album’s sessions in 1986-88.

Asked if there are many other out-takes or unreleased songs in the vaults, and if another box set is likely, Scott says the only big cache of unavailable material now is the pre-Waterboys music from 1976 to 1982 – “all my teenage bands, early recording sessions, demos, etcetera.

“I have an ongoing conversation with the label who owns the copyright – Warner/EMI at the moment – about doing a two-CD set of the best of that, but it isn’t scheduled yet. My guess would be in about three years’ time.” One of Scott’s best-known songs remains The Whole Of The Moon. In his vivid memoir, Adventures Of A Waterboy, he says it came about one bitterly cold night in New York when he was demonstrating his songwriting prowess to his then girlfriend. Casting around for inspiration, his gaze fell upon the luminous full moon.

The song, which has recently been given a gorgeous cover by The Staves, was once described by filmmaker Richard Curtis as one of the greatest pop songs ever; moreover, Curtis added, its creator was one of the greatest pop stars of all time. Did Scott read those words? And does he ever tire of singing the song?

“I greatly enjoyed that article, even if I think he overstates my place in the pop music firmament,” he says. “Though I agree that Whole Of The Moon is one of the best pop songs ever, and I’m very proud of it.

“I still love singing it – I never get tired of it. Even now, I still find new things to do with it, like a ‘too high, too far, too soon’ repeat section towards the end, which came in during last summer’s festival season – the first time as an intuitive addition to the song one night when a lightbulb went off over my head.”

While we’re on the subject of classic songs I ask him about the writing of one of my own favourite Waterboys hits: A Pagan Place, the title track of the second album, written on an overnight train journey.

“From London to Ayr,” responds Scott. “Summer 1983. I had my Danelectro 12-string Bellzouki guitar with me, probably travelling with it loose, no case in those days. I don’t remember the actual writing now, just the fact of it. But I am pretty sure I had been strumming those chords (with the B string tuned up to D) for a few weeks already.”

The Waterboys are in the middle of an extensive tour, which includes a handful of Scottish dates, including Edinburgh’s Ross Bandstand on August 28. “Do you know,” says Scott, “I used to look at that bandstand when I was a kid and think, ‘I’d love to play on the bandstand’, when I had dreams of being a rock musician, and now I’m going to get to do it, so I’m pleased about that.”

In November, the band play Aberdeen’s Music Hall, Glasgow’s Royal Concert Hall and Barrowland Ballroom. “We did that [two Glasgow dates] on the last British tour, and it works well,” he says. “I’m sure we could play the SECC if we chose but it’s good to play those two venues, because they’re both great, and people can make the choice as to whether they want to stand up or sit down.”

Ah, the fabled Barrowland. In his memoir Scott describes it as the best venue in the world. Safe to assume that returning there is a pleasurable prospect?

“Yes, indeed. I’m especially looking forward to seeing the faces of our three new American bandmates when the floor starts moving and that Glasgow roar goes up to the ceiling and bounces back on itself again. There’s nothing like it.”

The band’s music, meanwhile, is to feature in a forthcoming movie by the Dutch filmmaker, Robert Jan Westdijk. According to its website, Waterboys is about a crime novelist and his cello-playing son who take a road trip together; the band, who were filmed in concert in Amsterdam last December by Westdijk, have a key role in the storyline.

The day after the Wickerman show, the band will be in Portugal, then on the road until early December. Says Scott: “This is a gigging year for me, so I’m not thinking beyond it, really. I’m writing a few new songs, so there will be a new record, presently, but I haven’t got a clear idea of what it is yet.”

Finally – any thoughts about headlining Wickerman?

“I’m very happy we got asked to do it. I’ve wanted to play it for a while, and I imagine it will be very alternative, a very creative atmosphere, nicely weird, and capturing a kind of organised looseness.

“That’s my guess, but I’m ready to be surprised too. If there’s some cool mod or northern soul acts at the Scooter Tent, I’ll try and catch ‘em.”

The Waterboys headline the Wickerman Festival this Friday, July 24. www.thewickermanfestival.co.uk; www.mikescottwaterboys.com