A £50million green prize fund fronted by Prince William and Kate Middleton has added the 18th richest person in the world to its backers.
The Earthshot Prize scheme aims to solve the world's environmental problems by offering a series of high-value awards over the next decade.
When the prize was launched in October last year it only had six 'founding partners' who would be funding the award.
But without any major fanfare or announcement a seventh has been added to the list: the Rob & Melani Walton Foundation.
It is not clear the exact date they joined the project, but they were not included on the list as recently as March this year.