"The bitter story behind the UK's national drink", 8 Sep 2015

Several of Britain's biggest tea brands, including PG Tips, Tetleys and Twinings, have said they will work to improve the tea estates they buy from in India after a BBC investigation found dangerous and degrading living and working conditions.

Harrods has stopped selling some tea products in response, and Rainforest Alliance, the ethical certification organisation, has conceded the investigation has revealed flaws in its audit process.

The joint investigation by Radio 4's File on Four and BBC News in Assam, north-east India, found workers living in broken houses with terrible sanitation. Many families have no toilets and say they have no choice but to defecate amongst the tea bushes...

A manager on an estate owned by the world's biggest tea producer, McLeod Russel, admitted there is "a huge backlog of repairs".

McLeod Russel's Assam estates supply tea to the companies that own PG Tips, Liptons, Tetley and Twinings..

One girl who said she was 14, was picking tea at the prestigious Doomur Dullung estate. She said she had been working full time for two months.

Doomur Dullung is owned by one of the oldest tea companies in the world, Assam Company, and supplies Twinings, Yorkshire Tea, Harrods and Fortnum and Mason...

Assam Company has called the BBC's allegations "baseless and false"...

In response to the BBC's other findings, Tata said it is committed to the "fair and ethical treatment" of people across its supply chain and said its membership of the Ethical Tea Partnership (ETP) demonstrated its commitment to improving conditions in the tea industry...

The welfare of workers is of "utmost importance", according to Fortnum and Mason, which pointed out all its teas are sourced in conjunction with the Ethical Tea Partnership.

Unilever, which owns PG Tips and Liptons, says it takes the issues the BBC has raised seriously, but that progress has been made. However, the company recognises "there is still more to be done to raise standards" and says it is "working with our suppliers to achieve responsible and sustainable practices".

Harrods says it has removed Doomur Dullung tea from its shelves in response to the BBC investigation, but noted it hasn't bought any tea from the garden this year.

Meanwhile Taylors of Harrogate, which owns the Yorkshire Tea brand, told the BBC the company was "extremely concerned" by the BBC's findings and said it was "investigating as a matter of urgency".