Belle and Sebastian's sound tracks - Sarah Martin on films and festivals

The musician’s life may seem a glamourous one, but while a globetrotting lifestyle offers highs, there are lows, usually on returning home from tour. For Belle & Sebastian’s Sarah Martin, we catch her barely recovered from jet lag following a trip to Canada before hitting the high seas in the band’s floating festival, the Boaty Weekender.

“I shut my eyes and pretend I’m asleep and hope the pretence becomes real,” she says of her return flight, which hadn’t offered much in the way of rest. “It’s not high value sleep in a seat up the back of a plane.”

However, it was a worthwhile trip for the multi-instrumentalist, which took in the Calgary Folk Festival - an event which, perhaps like our own Celtic Connections, isn’t as ‘folk’ as you’d think with the Scottish indie heroes heading the bill. “The vibe was quite chilled and relaxed,” she recalls.

Martin’s own musical beginnings were on violin - so, not fiddle - playing in the school orchestra.

“I wanted to play flute but wasn’t big enough, so I had to play recorder,” she says of schooltime music. “You could guarantee a couple of days off a couple of times a year... but if you’re a kid that‘s a fairly social, good way to learn with a few friends.”

On the video for new single ‘Sister Buddha’ she can be seen tackling a somewhat larger instrument than the classic school xylophone. “That’s more for show,” she laughs - “tubular bells do look good!”

The single comes from a new album ‘Days of the Bagnold Summer’ - which is in fact a soundtrack, the movie the directorial debut of Simon Evans, who previously played Will in The Inbetweeners.

Although not in cinemas until next year, the film had its premiere on the Norwegian Pearl - the ship commandeered by her band for a four day cruise around the Med with Belle and Sebastian playing along with a hand-picked host of acts including Mogwai, the newly-reunited Camera Obscura, Django Django, The Vaselines and Honeyblood.

“It’s really really good,” she says of Evans’ first film,”it’s kind of a similar tradition to ‘Storytelling’” (which the band scored for Todd Solondz in 2001).

“It’s us making a record we want to make but with some sort of tentative links to the content of the film… so it’s half instrumentals and half songs... I think it’s turned out really nicely.”

Based on a graphic novel, its big names are Tamsin Greig and Rod Brydon, and stars Monica Dolan and Elliot Speller-Gillott (from W1A and Uncle respectively).And the band will be prepared for any future soundtrack work. “We’d embarked on a self-directed project to make ourselves an instrumental library,” Martin reveals, “and to put it out as EPs.

“Simon Bird - had told someone he wanted something ‘like’ a B&S soundtrack, and they knew we weren‘t as unapproachable as he might have thought, so he was told ‘if you want something like Belle & Sebastian maybe ask Belle & Sebastian!”

“Since we saw the film I see Monica Dolan in everything,” Martin smiles, "she’s so great. The original book the film’s based on is kind of focused on the teenage boy whereas the screenplay was written by the film director’s wife Lisa and is much more focused on the mother.”

And though the film won’t appear till next year, the album is out in September. “Our record company aren’t going to describe it as a Belle & Sebastian album as they want us to do a regular album of 11 or 12 songs - so this isn’t your big pop statement, but it was a really... pleasurable thing to do.”

As well as the silver screen the band’s songs will also form the backdrop to a play. 'If You‘re Feeling Sinister; A Play With Songs’ stars Sarah Swire of ‘Anna and the Apocalypse’ (who also appeared in Stuart Murdoch’s 2014 film ‘God Help The Girl) and Alan McHugh, a familiar face on ‘Taggart’ and ‘Limmy’s Show’.

However, this was rather less of a joint venture. “Literally none to be honest!” Martin laughs when asked how much of a collaboration the Edinburgh Festival play would be. “I know that Stuart (Murdoch) met the people and gave them his blessing, but it’s someone else’s story and idea and it’s just kind of pegged out by some of our songs.”

It seems that any greater involvement was stymied by the fact that the album the play draws from - Sarah Martin’s first with the band - is almost 23 years old. “Quite soon before we went on tour one of the people got in touch asking for access to ‘stems’ (the individual digital tracks from recording sessions).

“Stuart was asking ‘is there any way...” but of course we didn’t do stems in those days; it was all recorded to tape - so they’re on their own with that one!

Sadly there are no UK dates planned until that next album - so it’s a shame that the original Boaty Weekender idea didn’t come to pass. “I think the original idea was more to be going round Britain in a ferry,” Martin recalls. Less luxurious that their chartered liner.

You suspect that this high life might be something that she and her bandmates could get used to. As Martin admits, “It’s got proper beds and everything - which is more than you can say for a tour bus!”