The band traditionally stages two pre-festival warm up concerts on the Monday and Tuesday before the festival opens its gates. This year's concert dates are August, Monday 5 and Tuesday 6.
In previous years Fairport has invited guest musicians to join them on stage during the Tuesday warm up gig but this year the invitation will include the Monday night as well.
The gigs will take place at the Banbury Trades and Labour Club on West Bar Street.
The augmented line-up - already dubbed 'Fairport Extension' - will include guest appearances by friends of the band, including former drummer Dave Mattacks.
They will perform rarely-heard songs and instrumentals from the band's vast back catalogue.
Fairport bassist, Dave Pegg, said: "We're really looking forward to playing as a ten-piece band. It will allow us to play the elaborate musical arrangements which featured on past Fairport albums.
He added: "We don't often get a chance to play these 'big production' numbers live on stage.
"Although guests are usually restricted to the Tuesday night warm-up, we will invite them to play at to the Monday show as well so that everyone gets a chance to hear the extended repertoire.”
Fairport expect both nights to sell out in advance and recommend booking in good time. Tickets are on sale now from the band's website www.fairportconvention.com.