"Suntan" is the agency's fourth offering since gaining the account in December, following the closure of the then incumbent agency, D'Arcy.
In keeping with the theme of the previous three executions, the ad uses humour to project the message that Tetley is a fortifying drink that should be taken before daunting tasks.
The ad shows a butler drinking a cup of Tetley while a voiceover states: "A cup of Tetley and you're ready for anything."
The nervous butler is then summoned to the garden to apply suntan lotion to the Barbara Cartland-style lady of the house.
A voice ends the ad with the line: "Ready, Tetley, go."
The ad was produced by the creative team of Agnus Macadam and Paul Jordan.
It was directed by Pedro Romhanyi, through the production company Outsider.
"Suntan" will break during Sunday's episode of Coronation Street, with the TV schedule focused around other primetime programmes.
It will be supported by national radio slots and a national poster campaign.
Media buying and planning is through MediaVest.
Barry Cook, the chairman and managing director at Leo Burnett, said: "This new campaign portrays some of life's everyday challenges in an amusing way. In each ad, the key protagonist's effort to meet the challenge is fuelled by a cup of Tetley tea."
Since it ditched the Tetley Tea Folk, the brand has become a market leader in both value and volume, enjoying an increased share of the market compared with its rival PG Tips.