They replace Jennifer Saunders in the commercials, and follow in the footsteps of Rowan Atkinson, Alan Whicker and Jennifer Aniston.
The will play two friends driving across America, living out of a car. Mangan’s character is hapless, while Rhind-Tutt is the sensible one, always ready with his credit card.
The ads first will debut on ITV1 on Monday, after Life Begins.
The 40 and 60-second TV slots will be backed by a print advertising campaign.
Barclaycard’s Gary Twelvetree said: ‘We are delighted that Rhind-Tutt and Mangan are the new faces of our latest advertising campaign.
‘For this campaign we wanted a comic duo who would communicate the benefits of the Barclaycard Flexi-Rate card in a fun and visual way. The actors’ on-screen chemistry fitted the creative perfectly.’
