The sale of The Observer to Tortoise Media has been signed, kickstarting plans to shake-up the world’s oldest Sunday newspaper with a new website and daily digital content.

Tortoise is buying the media business from Guardian Media Group and the Scott Trust.

Acting editor Lucy Rock will become the newspaper’s editor of print and James Harding, co-founder of Tortoise, will become its editor-in-chief.

We respect the fact that people have had different views on the best way forward for The Observer

As part of the deal, Tortoise will take on all staff members who wish to stay with The Observer, it was confirmed on Wednesday.

Earlier this month, journalists at The Observer and Guardian went on a 48-hour strike in protest at the sale.

Tortoise plans to combine its newsroom with that of The Observer’s 233-year-old newspaper to create a daily digital Observer, including a new website, podcasts, video content and newsletters.

This will be developed throughout 2025, with a focus on arts, ideas and news content, as well as plans to build a new business and economics team, expanded science, technology and health coverage, and a dedicated sports desk.

Tortoise has pledged to invest £25 million in The Observer, with a commitment to continue printing on a Sunday.

The Scott Trust has also become a key shareholder with equity investment in the company, while the Guardian Media Group has signed a five-year agreement to pay for print and distribution services and marketing.

Ms Rock said it was a “huge privilege to be entrusted with the editorship” of The Observer and that she was looking forward to building a “dynamic digital identity” for the paper.

Alan Rusbridger, British journalist and former editor-in-chief of the Guardian, said the sale will create a potential rival to its former sister publication.

He wrote on X: “If James Harding’s figures are to be believed the Scott Trust has just enabled and funded a potentially powerful competitor to the Guardian in the liberal media space.”

The first edition of The Observer under Tortoise ownership is expected to be published in the spring.

Tortoise said it promised to meet all key employment terms for any members of staff, as well as freelancers and contributors, who wish to keep working for the company.

It has also said its investment would lead to at least 12 new roles for staff reporters and a near-doubling of the editorial budget.

Tortoise was founded in 2018 by former BBC executive and The Times editor Mr Harding and Matthew Barzun, a former US ambassador to the UK.

Mr Harding said: “We respect the fact that people have had different views on the best way forward for The Observer.

“We all share a passionate belief in its future and the privilege of working for it.

“We can’t wait to bring the brilliant people in both our newsrooms together and get to work on the journalism we care about.”