MCBD was chosen to handle the business ahead of Campbell Doyle Dye. Wieden & Kennedy pulled out of the running on the eve of the pitch because of fears of a clash with its newly acquired Starbucks account in the US.
Andrew Dobson, the tea company's marketing manager, cited MCBD's "strategic thinking and its understanding of the tea consumer" as the reasons for the agency's appointment.
New advertising will begin later this year, culminating in a reappraisal of the Tetley brand, which the company began two years ago. The Tetley business was won by D'Arcy, now part of Burnett, in 1979.
The brand has struggled to position itself since ditching the famous Tetley Teafolk characters, who were regarded as too old-fashioned, northern and working class for the brand's new image.
More recently, Tetley's advertising has presented it as a healthy, fashionable drink to younger and more affluent consumers under the theme: "Ready, Tetley, Go."
"Today we have record brand shares and are extending the brand's presence into key growth areas of the tea market," Dobson added. "I'm delighted we are able to mark the growth of our brand with fresh new advertising from a dynamic agency."
Helen Calcraft, the MCBD managing director, said: "Tetley is a fabulous win for us and we're thrilled to be working with such a famous brand. The chemistry with Tetley is extremely strong and we feel confident that the advertising will be all the better for it."