By Tim Masters
Entertainment correspondent, BBC News
Less Is More will be the band's 16th studio album
Marillion are allowing a fan to play tracks from their new album on the fourth plinth in London's Trafalgar Square on Tuesday evening.
Richard Loveridge, 38, will spend his hour on the plinth talking about his 26-year love of the prog-rock veterans.
"My longest adult relationship has been with these five men, so I wanted to frame the story of my life with the story of Marillion," he said.
The fourth plinth is part of Antony Gormley's One and Other exhibition.
The project, which started on 6 July, has seen a different person take a place on the plinth every hour.
Mr Loveridge, from Leominster, Herefordshire, asked the band for permission to play some of their music last week when he heard he had got a spot on the plinth.
"I was offered a place quite late - someone had dropped out - so I had to come up with something to do in a week," he told the BBC.
'Sworn to secrecy'
He was amazed when the band offered two new songs from the acoustic album Less is More, out in October.
Richard Loveridge - pictured with his son - has been a fan since 1983
"The relationship between fans and band has got closer and closer to the point where they can trust me as a fan to play music to the public from an album that hasn't been released," said Mr Loveridge.
"I was sworn to secrecy and promised not to let them loose on file-sharing!" he added.
The tracks are Hard As Love and This Is The 21st Century - both re-workings of tracks from Marillion's back catalogue.
Marillion manager Lucy Jordache said that because some of the songs on the album were quite gentle, the band carried out an unusual sonic experiment with a borrowed JCB.
"Someone got in with a stereo and we raised it 30 feet up in the air and stood at the bottom shouting out "next track!
that one's too quiet
next track..." until we came up with the two that would sound best on a plinth in Trafalgar Square," she said.
Mr Loveridge, who has been fan since the band's first album Script For A Jester's Tear in 1983, said there had been two distinct reactions to his plinth plans.
"People I know have said: 'Oh God, you're not still banging on about them are you?' - which is the reaction I've had for a quarter of a century.
"Fans have been incredibly positive - I know there's somebody flying over from Rome to come and support me and to listen.
"I've had messages from all over the world from people saying they'll tune in and watch, so even if it is a dank and empty square tonight I know there will be people across the globe hanging off my every word."
Richard Loveridge will be performing in Trafalgar Square at 2000 BST on Tuesday 1 September.