Image copyright Anthrox Studio Image caption (L-R) Black Midi's Cameron Picton, Morgan Simpson, Matt Kwasniewski-Kelvin and Geordie Greep as avatars in a promotional band image

From the Brit School to the Mercury Prize, Black Midi are defying all musical convention.

For even the most hyped of new acts, having your song played on national radio is a huge deal. Such slots are viewed as premium cultural real estate.

So for Black Midi to be given carte blanche to "fill 10 minutes with whatever they fancy" ahead of the drivetime news felt like a strangely watershed moment.

The experimental young guitar slingers were afforded the luxury by 6 Music DJ Steve Lamacq in June, around the release of their Mercury-nominated and divisive debut album Schlagenheim.

The 43-minute LP is made up of tracks born out of similarly lengthy impromptu jam sessions, where they would ride the waves of repetition until they could see something resembling the musical shore.

While the prospect of improvising to millions of listeners would give your average new indie band heart palpitations, frontman Geordie Greep says they are more comfortable wigging out on air than being plagued by the protocol of playing three-minute pop songs.

'It's kind of silly really'

"It's quite silly how people break up music a lot of the time with 'it has to be this long for whatever,'" he tells the BBC.

"Because when you listen to an album, even though a lot of the songs are separated, you just hear it as one song, you know?

"When you think of an album you like, you might think of it song by song - but it is just one thing.

"So the whole politics of it are kind of silly really."

"Stuff like [their 6 Music appearance] is quite fun to do," Greep goes on. "And the pressure of having it live on the radio is quite cool, I think.

"When we made the album, what we tried to do is have it as a separate thing to how the songs are live, so that it's not a game of trying to replicate it.

"Just the two things both have their own pros and cons, and people can like the album and like the live show without having to compare."

Black Midi's wildly eclectic debut has been described by critics as everything from thrilling to frustrating.

Greep says they don't mind being the Marmite band of the moment, loved and loathed in equal measure.

"That's never a bad sign," he laughs. "At least that kind of implies passion or whatever. There's nothing worse than something mediocre.

"Even if something's terrible, at least there's something to talk about there."

The Mercury Prize panel clearly fall into the former camp, having named them on the 12-strong list for Thursday's prestigious annual album award.

They're known for tipping their collective cap to one jazz act (Seed Ensemble this year), but Black Midi's often uncategorisable sound and Greep's off-kilter vocals make them another left-field selection.

Another tradition is for each nominee to perform a track in front of their peers and the Greater London four-piece are unlikely to find the event's organisers as accommodating as Lamacq.

Image copyright Getty Images Image caption Greep (in hat) says the title of the band's album Schlagenheim represents "a fictional location"

Near DT MI, their record's only sub three-minute track, or the more "radio-friendly" Ducter seem like potential candidates to be played on the night.

Others, like Western, breach the eight-minute mark and, in the case of lead single Bmbmbm, descend into a kind of repetitive madness that would even test fans of The Fall.

School of (experimental) rock

The 19-year-old cites Marvin Gaye and Frank Zappa as his two main musical influences but the band, who met at The Brit School, call to mind classic Krautrock from the likes of Neu! and Can when they are at their motorik best.

Their old school may have helped launch the careers of such pop stars as Adele, Amy Winehouse and Jessie J. Yet its latest graduate singer suggests there was always room for more "adventurous" abstract sounds on the syllabus.

"Obviously those people will be the ones known as coming from the Brit school because they are making middle-of-the-road music," claims Greep. "So they are inevitably going to be the names that are said.

"But there's a lot of people, producers and stuff, who you would never expect to have gone that also did go to the school, so it's like quite a false stereotype of it.

"They really do push you to listen to all sorts of stuff and try out all different forms of music and it's never steering you into a mainstream kind of direction - it's whatever you want to do."

Schlagenheim is out now. The winner of the 2019 Mercury Prize will be announced on Thursday.

Follow us on Facebook, or on Twitter @BBCNewsEnts. If you have a story suggestion email entertainment.news@bbc.co.uk.