The poll, which coincides with International Tea Day, comes as the Women's Institute and Traidcraft send 20,000 postcards to the five brands that dominate the market - PG Tips, Tetleys, Twinings, Typhoo and Yorkshire Tea - calling for them to go Fairtrade.
Camilla Porter, Traidcraft head of campaigns, said: ‘The big tea brands are lagging behind popular consumer brands like Starbucks, Tate & Lyle, Cadbury's Dairy Milk and Nestlé's KitKat, which have all made a commitment to Fairtrade.
‘Right now there are 80 registered Fairtrade tea producers with spare Fairtrade tea to sell. PG Tips, Tetleys, Twinings, Typhoo and Yorkshire Tea have 72% of the market. Their commitment to Fairtrade would make a lasting difference to the lives of millions of tea workers,' she added.