He said: “We, I say we, my band will play @carfestevent South Sat night, first ever gig all for @bbcin.
“Learning in a scout hut then 40k people! Be nice out there as every spare min spent practising,”(sic) James continued.
Car Fest is a family festival which is held in Cheshire and Hampshire, and was set up by Chris in 2011.
Before James appeared on stage at the music and motoring festival, the official Facebook page announced he would be making an appearance.
They wrote online: “The one and only James Martin is at home practicing for his musical guest appearance on the CarFest South!”