Courtney Barrett opened the Pyramid Stage earlier today (June 27)
British pop star was due to perform at California festival on Friday
The singer-songwriter reveals he's given up alcohol : 'I had to stop, I couldn't keep up'
The British singer was introduced by guest host Dwayne 'The Rock' Johnson
The episode will be hosted by Dwayne 'The Rock' Johnson on March 28
The gig will take place next month at Brixton Electric
The actor sings and dances along to the track