Crowds gathered in Trafalgar Square for a vigil in honour of the four innocent victims of the terror attack in London.
As the bells of nearby church St Martin-in-the-Fields chimed 6pm, a hush fell over the crowd yesterday.
Dignitaries, police and clergy, including Buddhist monks in brown robes, gathered on the steps leading to the National Gallery on the north side of the square.
There was a strong sense of solidarity among the thousands who attended. Muslims mingled with Jews and people stopped to thank the police for their work.
After a minute's silence, the Home Secretary, the Mayor of London and the Acting Metropolitan Police Commissioner lit three oversize candles to applause from the growing crowd.
Sughra Ahmed, a Muslim who travelled from northwest England, was reduced to tears by a woman who went out of her way to embrace her.
"Britain is one," she said. "An attack on one is an attack on us all."
A police officer, a mother-of-two and an American tourist were killed in the brutal attack in the heart of London.
Last night police confirmed that a 75-year-old man who had been in hospital following the attack had also passed away.
Another 40 people, from 11 countries, were injured in the bloodbath. Twenty-nine needed hospital treatment. Six remain in a critical condition.
There of the four innocent people killed the attack were:
Pc Keith Palmer
PC Keith Palmer (48) was a former soldier who had been with London's Metropolitan Police for 15 years.
"He was someone who left for work ... expecting to return home at the end of his shift, and he had every right to expect that would happen," said Scotland Yard's most senior anti-terror officer, Mark Rowley.
In an emotional tribute, Tory MP James Cleverley, said: "I've known Keith for 25 years. We served together in the Royal Artillery before he became a copper. A lovely man, a friend. I'm heartbroken."
The Mayor of London, Sadiq Khan, said: "Keith Palmer was killed while bravely doing his duty - protecting our city and the heart of our democracy from those who want to destroy our way of life. My heart goes out to his family, friends and colleagues. He personifies the brave men and women of our police and emergency services who work around the clock to keep us safe."
Tributes were paid by many MPs, including former Labour leader Ed Miliband. "We all mourn for PC Keith Palmer and send the deepest condolences to his family. He died protecting all of us at Westminster."
Another Labour MP, Keir Starmer, said: "Thank you PC Keith Palmer. No need for words about us or Parliament. Just all thoughts to your family."
Metropolitan Police Federation chairman Ken Marsh expressed "deepest sympathy" to the officer's family.
"This incident sadly shows the dangers our colleagues face on a daily basis. They show incredible bravery protecting the public," he said.
The husband of English MP Jo Cox, who was murdered in West Yorkshire last year, said: "The name I will remember from the Westminster atrocity is PC Keith Palmer, not his killer."
Brendan Cox, whose wife was stabbed and shot by a right-wing extremist outside her constituency office, said the identity of the terrorist was irrelevant.
Aysha Frade (43) was a British woman of Galician origin. She was leaving nearby DLD sixth-form college, where she was a department head and Spanish teacher, when she lost her life in the attack.
She was crossing Westminster Bridge to pick up her children, aged eight and 11, from school when she was mown down by the terrorist's car.
Speaking outside the family's former house, neighbour Patricia Scotland said she had known Aysha's husband, John, all his life, and first met Aysha when they started dating.
She added that the couple had been "lovely family" and had two young girls together.
"The last time I spoke to them was at New Year and Christmas. I spoke to them on the phone, you know, to wish them well.
Mrs Frade was "a highly regarded and loved" member of staff at DLD College, said the principal Rachel Borland.
Mrs Borland said in a statement: "We are all deeply shocked and saddened at the news that one of the victims yesterday was a member of our staff.
"All our thoughts and our deepest sympathies are with her family. We will be offering every support we can to them as they try to come to terms with their devastating loss.
"Aysha worked as a member of our administration team at the college. She was highly regarded and loved by our students and by her colleagues.
"She will be deeply missed by all of us."
Kurt Cochran (54), an American tourist, was also mown down on Westminster Bridge by the terrorist's car.
His wife, Melissa, was also injured in the attack. She sustained a broken leg and rib but it is not believed to be critical.
Mr Cochran, an engineer, was passionate about music and owned his own music studio in Utah.
Mrs Cochran's sister, Shantell Payne, wrote on Facebook: "With a heavy heart I must pass the sad news of our beautiful brother, father, husband, son and friend Kurt Cochran.
"He could not overcome the injuries he received in the London terror attacks.
"This pain is so heart wrenching and raw it has rocked our family and all that knew him to its core."
"We will miss Kurt beyond words. We love you Kurt. RIP."
Mr Cochran appeared to have been travelling around Europe this month, having posted photographs of his recent visit to Ireland, Scotland and Germany on his Facebook page.
He described himself as a "self-starting business owner" and spoke frequently of his passion for music.
In a 2014 interview with a local newspaper he said he "grew up in Maryland, lived in Texas for a while, then ended up in Salt Lake City in 1983.
"As I grew older, hard rock/heavy metal took over as my favorite genres, like Black Sabbath, Judas Priest, Rush and Aerosmith."
The music fan managed to achieve his dream of opening his own recording studio in 2007, and it appeared to be a roaring success, with customers giving it rave reviews.