Winston Churchill's great-grandson has delivered a petition with more than 55,000 signatures to Downing Street, demanding action from David Cameron to protect Afghan interpreters who served on the front line in Helmand with British troops.
Alexander Perkins said the UK owes the interpreters a "huge debt" and they will be "sent to their deaths" if they are not at least offered asylum.
Earlier this year the Government proposed a relocation package for the interpreters which means those who served on the front line with British troops for more than a year could be eligible for a five-year visa to the UK.
But speaking as he handed in the petition, Mr Perkins said only those who have worked on or after January 1 this year would be eligible.
Mr Perkins, who served two tours of duty in Afghanistan as a captain in the Scots Guards, said the pledge falls "short of the mark".
He said: "The reality is that at the end of the tour, when we go home they're left in Afghanistan and their homes are potential warzones.
"And if local insurgants or local informants have put two and two together and worked out that these guys are interpreters and facilitating Isaf (International Security Assistance Force), whether it be the Brits or the Americans, their lives and the lives of their families are at risk.
"We're pulling out in 2014 and we're going to leave these guys behind.
"I'm not saying they're all going to be killed, but there's a fair chance that a large number of these guys are going to be persecuted by the Taliban, and some of them probably will end up being killed."
Mr Perkins, who started the petition on change.org calling for greater protection for the interpreters, went on: "We want the Government to review policies surrounding Afghan interpreters and change it so it is more encompassing and those who served alongside us in Afghanistan are granted asylum here in the UK.
"Other nations in Isaf, the New Zealanders and the Americans, actually grant their interpreters asylum and nationalise them.
"The New Zealanders go as far as to put them in houses, give them some start-up money, and help them find a job for them and their families, and I feel that we should be doing the same for these brave men who stood shoulder to shoulder with British forces."
Mr Perkins, 27, said the interpreters were vital to British troops.
"We owe them a huge debt. Without them our position in Afghanistan would have been untenable - we wouldn't have been able to interact with the local population, we wouldn't have been able to work so closely with the Afghan security forces, whether they be the army or the police," he said.
Asked what he thought his great-grandfather would have thought of the situation, Mr Perkins - whose mother was the former prime minister's granddaughter - said: "I think he was obviously a politician and a soldier, I think he would have looked at this from a soldier's perspective.
"These interpreters are brave men, they stood up and helped us ... and now it's a case of us doing the same for them."