Dozens of Metropolitan Police officers, who had served alongside the victim, gathered outside the headquarters for a moment of silent reflection after his shocking murder.
The 48-year-old husband and father was attacked by Khalid Masood with two knives in the grounds of the Houses of Parliament.
After the news of his tragic passing, tributes flooded in describing PC Palmer as a “lovely man” and “hero” who “gave his life in defence of the public”.
Theresa May led tributes to the 48-year-old, addressing MPs in the House of Commons, she said: “He was every inch a hero and his actions will never be forgotten.”
Police officers paid an emotional tribute to London terror victim PC Keith Palmer
Keith Palmer was an amazing guy, he always wanted to be above and beyond
Conservative MP James Cleverly, who served alongside the victim in the army also gave an tearful speech about his former colleague.
He said he “first met PC Keith Palmer 25 years ago as gunner Keith Palmer at Headquarters Battery 100 regiment, Royal Artillery.
“He was a strong, professional public servant and it was a delight to meet him here again only a few months after being elected.
“Would my Right Honourable friend the Prime Minister in recognition of the work had he did and the other police officers and public servants here in the house do, consider recognising his gallantry and sacrifice formally with a posthumous recognition?”
Mrs May replied: “I thank my Honourable Friend for the obvious compassion, but passion for which he has spoken about an individual he knew.
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“And he bears witness to the tremendous public service that Keith Palmer had given this country in so many ways.
“And having served in our armed forces and then come here to this place and pay the ultimate sacrifice here at the heart of our democracy, I can assure my honourable friend that the issue he’s raised is of course one that will be considered in due course.”
Labour Party leader Jeremy Corbyn, in his own address, said: “I express my condolences to the family and friends of police officer Keith Palmer who gave his life yesterday in defence of the public and of our democracy.”
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Speaking after officers paid tribute to their fallen colleague, David Darby, a former military colleague of PC Palmer, told Sky News of his “amazing” friend.
He expressed the “shock” of hearing the news, adding: “He was an amazing guy, he always wanted to be above and beyond, and that’s why he joined the police.
“He died on duty defending the people of London.”