During his act at the Lone Wolf Comedy Club Atic bar in Bicester, the popular comic born Paul Barbieri sat on a chair and laid back for five minutes.
Audience members were under the impression this was part of the act and continued to laugh at the supposed joke, with no one aware that Cognito had actually suffered a stroke.
The reality of the situation only dawned on audience when the show compere eventually approached the stage and after 10pm and called an ambulance, the ambulance crew pronounced Cognito dead at the venue.
A statement from the ambulance service read: 'We were called at 22:11 last night to Crown Walk in Bicester to a medical emergency. We sent a rapid response vehicle and an ambulance crew but sadly one patient passed away at the scene.'
Paul Barbieri was born in 1958 in London, he took up the stage name Ian Cognito when he started performing in the 1980s.
While the Bristol-based comedian did not achieve the mainstream success of some of his colleagues, he was praised by many in the industry as a 'one of the greats' and a 'true maverick'.