The Observer, established in 1791, is based in London and has been a separate, sister paper to The Guardian since it was bought by GMG in 1993. Its journalism is published online on The Guardian website.

“Tortoise and GMG have been in discussions about the terms of a potential deal and the two companies have now agreed to enter formal and exclusive negotiations,” said Tortoise.

Tortoise, the “slow” newsroom, launched in 2019. It approached GMG with an offer to buy The Observer and a commitment to invest over £25 million over the next five years in the editorial and commercial renewal of the title.

“Tortoise will continue to publish The Observer on a Sunday and build the digital Observer, combining with Tortoise’s podcasts, newsletters and live events.”

James Harding, Editor and Founder of Tortoise, said: “We think The Observer is one of the greatest names in news. We believe passionately in its future – both in print and digital. We will honour the values and standards set under The Guardian’sgreat stewardship and uphold The Observer’s uncompromising commitment to editorial independence, evidence-based reporting and journalistic integrity.

“Like its many, many loyal readers, we admire the strength and heart of The Observer’s reporting, we prize its original, unbiddable thinking and we love it for its passions: food, music, film and art. George Orwell described The Observer as ‘the enemy of nonsense’; we’re excited to show readers, old and new, that it still is.”

Guardian Media Group CEO Anna Bateson said: “This is an exciting strategic opportunity for the Guardian Media Group. It provides a chance to build The Observer’s future position with a significant investment and allow The Guardian to focus on its growth strategy to be more global, more digital and more reader-funded.”

Katharine Viner, editor in chief of The Guardian, said: “This has the potential to be a very positive thing for both The Observerand The Guardian. My number one priority is a future in which both titles continue to thrive and deliver high quality journalism to our readers. It is extremely important to me that The Observer, with its excellent journalistic reputation, loyal readership and heritage as the world’s oldest Sunday newspaper, is in good hands.”

Matthew Barzun, the former US ambassador to London appointed by President Obama, is the chairman of Tortoise. It is backed by a range of financial investors including David Thomson, chairman of Thomson Reuters, Lansdowne Partners and Local Globe, although no investor has a controlling interest.