As dusk settled over an eerily silent horde of Communist Red Guards gathered outside of the British Embassy in Beijing, diplomat Sir John Weston's worst fears were confirmed.
The date was August 22, 1967, and Chinese authorities had issued an ultimatum that the British government release individuals convicted in an open court for perpetrating terrorist attacks in Hong Kong.
It was as Mao's Cultural Revolution began to pick up pace, and nationalist xenophobia had already spawned violence and demonstrations outside many of the other consulates in the capital.
The day wore on, and a mass of people described by media reports later as 10,000 strong, gathered outside of the Embassy, patiently waiting as if for a signal.
The diplomats and their wives were prevented from leaving the building by PLA sentries, who claimed that their safety could not be guaranteed if they were to pass close to the camped mob.
Due to the phone lines being cut, friends at neighboring consulates were unable to warn them that they had seen men with petrol cans and oil drums amongst the crowd that advanced on the British Embassy.
The ultimatum expired that evening and with it the seeming passivity of the Red Guards. At 10.30 p.m. a flare was fired into the night sky. At that point, the entire massed demonstration outside the Embassy rose like one person to their feet and swept over the wall and into the compound, Sir John recounted.
Later they learned that the last message London had received from them before the communication wires were cut was simply "they are coming in."
The 18 men and five women then withdrew into the Embassy strong room, where they turned out the lights and kept quiet so as to not attract attention. Smoke poured in through the smashed windows of the room as the building was torched and above the chaotic din they could hear the frenzied shouts of "Kill! Kill!"
Red Guards with battering rams had succeeded in breaking down the walls of one side of the building. Sir John explained that what gave the sacking of the Embassy the air of an officially sanctioned attack was that a specialist group had actually penetrated the consular communications room and stolen equipment which diplomats had used to send encrypted messages back to London.
They realized then that they were on the receiving end of a deliberate and planned attack on the Embassy.
After forty-five minutes, the heat of the blaze coupled with the smoke made it difficult for the Embassy staff to breathe. When it became too dangerous to stay in the building, it was agreed that the group should exit the building via a secret emergency passageway.
As they came out amidst the chaos, Sir John described what befell them as something like a scene from a Wagner opera.
The entire night sky was ablaze because the building was on fire, and the whole compound was seething with young Red Guards. As soon as they saw the Embassy staff, they set upon them like wild animals.
Sir John clung to his young wife as hands clawed them in what he described as a struggle for their very existence. At one point, when it seemed as though his wife was going to be dragged away by her hair, Sir John recalls sinking his teeth into the arm of the assailant in order to make him let go.
Hands went up skirts and men's private parts were screwed in fists as they attempted to escape from what he described as a moving sea of very angry people.
The group reached the perimeter and managed to persuade the PLA sentries who had remained immobile throughout the ordeal, to escort them to safety.
Many of the staff members suffered long term injuries and one of the men died from his wounds shortly afterwards.