Last week, he launched a crowdfunding campaign for legal fees to "locate and safeguard" the explorer.

He wrote that the fundraiser had been created as "a result of our concern and desperation" after trying "multiple avenues" to locate his stepfather.

Arabella Pepper, the younger sister of Sir Ranulph's late first wife Ginny, told BBC Newsnight that she had not been able to see her former brother-in-law for over a year.

"All his friends and family want to see him and take him Toblerones and cheer him up, but we don't know where is, and he's not available, he's not accessible - that's what worries us," she said.

She alleges that she was only able to see him in July 2025 after she admitted herself to a care home where she had been told he was staying.

"The first thing I said to him, apart from the usual greetings, was that everybody was worried about him, was looking for him, was longing to see him," Pepper told the BBC.

"The relief on his face was very obvious, and he said, send a message to everybody, send them my love, tell them I love them and tell them I'm longing to see them."

Posting on X, BBC world affairs editor John Simpson, wrote he was "horrified to hear what's happened to my good friend Ran Fiennes".

"He's the world's bravest man, and he's vulnerable. We must know what's happening to him."

Starting in 1967, Sir Ranulph has been the leader of almost 20 major expeditions, according to the Explorers Club.

His expedition to both the north and south poles came during the Transglobe Expedition, in which he led the first team to circumnavigate the globe from north to south.

Sir Ranulph has also enjoyed a career as a prolific travel writer, as well as authoring fiction, non-fiction and biographies.