Armed police moved in as the forgotten heroes of the Cold War protested outside the Ministry of Defence.
Dozens of atomic test veterans and their families marched down Whitehall protesting the "no risk, no rigour, no justice" of the repeated failure to award them a medal.
The Missing Medal demo stopped traffic and saw families in tears as they laid wreaths at the Cenotaph on the 65th anniversary of Operation Grapple X, Britain's first H-bomb, and ahead of Remembrance Sunday. Test veterans are plagued by cancers, miscarriages, and birth defects in their children.
Julie Soane, 60, of Guildford, said: "My dad Eddie was at the biggest bomb test, Grapple Y, in 1958.
"He died in 2019 of bowel cancer and a brain tumour, and I'm blind in my left eye. It means a lot to be able to lay this wreath for him and the other boys today. This is the best we've got."
The Mirror reported earlier this week that a secretive medal committee has ruled against a medal for the tests, judging there was not enough "risk or rigour" to them. It is now up to Prime Minister Rishi Sunak to seek an audience with the King to recommend one be granted.
Supporter Al Murray said: "The more I hear about this scandal the angrier I get. The medal is the bare, bloody minimum they could do. These men are the cornerstone of our nuclear deterrent but they're being shunned and traduced."
He added: "Everyone in uniform right now needs to know this is what could happen to them in the future."
Veteran Bill Lawrie, 91, of Hornchurch, Essex, who took part in clean-ups at Christmas Island in 1961, joined Op Grapple survivor Brian Unthank, 84, of Erith, Kent, who has had 87 skin cancers removed and endured 13 bouts of radiotherapy.
Brain said: "Rishi Sunak should come down here, stand to attention and tell us there'll be a medal next week, but there's no chance in hell of that happening."
Simone Pasquini, 54, flew from America to honour her father Joe who flew through the mushroom clouds in a 'sniff' plane. She said: "A medal would be recognition of what happened. To deny it, denies the truth of what they did."
Rebecca Wilshire, of Peterborough., whose father Roy served at highly-toxic tests in Australia in 1957, told how her brother died of cancer at 42, her two sisters had multiple miscarriages, and her parents once had a baby so deformed that the hospital forbade them from seeing it.
Shadow Attorney General Emily Thornberry said: "Every country in the world recognises the suffering of their nuclear test veterans and it's really about time the PM did the right thing."
Tory grandee Sir John Hayes MP said: "I've campaigned for years for these men's sacrifice and heroism to be recognised. The very least we could do is a medal."
The demonstrators spoke to media in Parliament Square at the foot of the statue of Winston Churchill, who began the cover-up in 1952 when he erased praise for the troops from his speech about the first bomb test on October 3, 1952.
But when they moved on to the MoD which has denied them recognition for 70 years, they were less than welcome.
After they observed a minute's silence, half a dozen armed police moved in, demanding to speak to organisers and telling them they could not leave wreaths on MoD property. When the protestors left, the police removed the tributes to the fallen.
"I hope you heard us," shouted Grapple veteran John Morris, 85, of Rochdale, as he turned to leave.
