Mounted police today moved in to hold back people gathering to mourn the death of Prince Philip - after Downing Street urged people not to gather outside royal palaces due to the risk of Covid.
Officers on horseback arrived at Buckingham Palace to control crowds of people who had gathered in their hundreds to mark news of the Duke of Edinburgh's death, at the age of 99.
Police on foot were also seen marshalling crowds as they attempted to keep a gap between mourners and the palace gates - where tributes have already begun piling-up.
It comes weeks after people, including the Duchess of Cambridge, were freely allowed to lay flowers and pay tribute to Sarah Everard at Clapham Common following news of the marketing manager's tragic death.
Today Downing Street asked mourners not to gather or lay flowers outside royal residences for the much-loved Duke due to the risk of Covid.
Hundreds of floral tributes have already piled-up at palace gates, including Buckingham, Windsor and Balmoral, following the announcement of Prince Philip's death earlier today.
An online book of condolence is now available on the royal website for those who wish to send a personal message of condolence, the royal family's Twitter account announced.
It added: 'During the current public health situation, Books of Condolence will not be available for the public to sign.
'The Royal Family ask that members of the public consider making a donation to a charity instead of leaving floral tributes in memory of The Duke.
'Those who wish to make a donation as a tribute to His Royal Highness are encouraged to give to a charity of their choosing or one of the charities or organisations which The Duke of Edinburgh supported in his public duties.'
Meanwhile a brief bulletin traditionally used to notify the public of key royal events such as births and deaths was taken down prematurely from the gates of Buckingham Palace due to Covid.
Usually the statement, on paper set in a foolscap imperial-sized dark wooden frame and which was put in place by Royal Household staff wearing black face masks, would have remained in place for 24 hours.
Around 30 people initially began queuing to read the sign before four police officers on horses stopped the crowds from gathering.
The Met Police today refused to comment on the operation when asked by MailOnline.
Meanwhile, a Cabinet Office spokesperson told MailOnline, said: 'The sad death of HRH The Duke of Edinburgh has been announced by Buckingham Palace.
'Although this is an extraordinarily difficult time for many, we are asking the public not to gather at Royal Residences, and continue to follow public health advice particularly on avoiding meeting in large groups and on minimising travel.
'We are supporting the Royal Household in asking that floral tributes should not be laid at Royal Residences at this time.'
Mounted police today moved in to hold back people gathering to mourn the death of Prince Philip - after Downing Street urged people not to gather outside royal palaces due to the risk of Covid
Downing Street has today asked mourners not to gather or lay flowers for Prince Philip outside royal residences due to the risk of Covid
It comes as hundreds of tributes pile-up at palace gates, including Buckingham and Windsor (pictured), following the Duke of Edinburgh's death this morning, at the age of 99
A brief bulletin, on paper set in a foolscap imperial-sized dark wooden frame, is traditionally used to notify the public of key royal events such as births and deaths - but it was removed prematurely today due to Covid
However Number 10 has insisted people avoid gathering at the gates today, urging mourners to stick to Covid guidelines and 'avoid meeting in large groups'
Huge crowds were today seen gathered outside Buckingham Palace as a lifelong supporter of the Royal Family laid a floral tribute
It comes as the Queen today announced with 'deep sorrow' the death of Prince Philip at the age of 99. Pictured: A mourner holds a Union Jack outside Buckingham Palace today
A group of mourners today added to the growing tributes outside Windsor Castle, where Prince Philip is said to have passed away earlier today
A woman adds flowers to the tributes at the railings at the front of Buckingham Palace today, as dozens of mourners are seen gathering in the background
Police were earlier today seen keeping mourners back from the gates, after Downing Street asked people not to gather due to the risk of Covid
Dozens of floral tributes were left at the gates of Buckingham Palace today, as police stood guard in a bid to keep mourners at a safe distance
Officers were also seen guarding the front of Windsor Castle earlier today, where flowers were also left in memory of Prince Philip
Flowers with condolence messages are placed outside Windsor Castle following the passing of Prince Philip, in Windsor
Crowds also gathered outside the royal residence of Sandringham, where flowers were laid in memory of Prince Philip today
It comes as the Queen today announced with 'deep sorrow' the death of Prince Philip at the age of 99.
She described her husband as her 'strength and guide' throughout their 73-year marriage and her 69-year reign.
The tradition of the royal notice outside Buckingham Palace
A brief bulletin, on paper set in a foolscap imperial-sized dark wooden frame, is used to notify the public of key royal events such as births and deaths.
Usually the statement remains in place for 24 hours.
When the Queen Mother died in 2002, a statement on headed Buckingham Palace notepaper, which features a royal crest, was posted on the gates.
A police officer stood guard over the glass fronted frame, which is usually fixed to the outside of the iron railings by two small metal chains on the back.
The deaths of George VI and George V were also announced this way.
For a sovereign, a notice is also placed on the railings of the house in which they died.
The traditional method of delivering royal news was used for, among other occasions, Prince William's birth in 1982 and Peter Phillips' in 1977.
When the Queen gave birth to Prince Andrew in 1960, some 2,000 people crowded around the railings to see the official confirmation.
For each of the births of Prince George, Princess Charlotte and Prince Louis of Cambridge, as well as their cousin Archie Mountbatten-Windsor, the same wooden frame was used to highlight their arrivals.
But on those occasions, the frame was placed on an ornate golden easel on the forecourt of the palace, inside the railings.
Announcements used to be hand-written but now are mostly typed.
The Duke of Edinburgh spent his final days at Windsor Castle with his wife, who he lovingly called Lilibet throughout their long life together, after a 28-night stay in hospital having been admitted in mid-February for an infection and a pre-existing heart condition.
Her Majesty announced her husband's death at midday as the Union Flag was lowered to half-mast outside Buckingham Palace and on public buildings across the UK and Commonwealth, while members of the public hugged and wiped away tears as they laid flowers in his memory - and messages of support for the Queen.
The Royal Family said in a statement: 'It is with deep sorrow that Her Majesty The Queen announces the death of her beloved husband, His Royal Highness The Prince Philip, Duke of Edinburgh.
'His Royal Highness passed away peacefully this morning at Windsor Castle. Further announcements will made in due course.
'The Royal Family join with people around the world in mourning his loss'.
Her Majesty, who remains at Windsor Castle, is now expected to enter an eight-day period of mourning.
She will not carry out any duties, even in private, while laws will not be given the Royal Assent and affairs of state will also be paused.
Mourners have today been laying flowers at Buckingham palace, Sandringham, Balmoral and Windsor Castle.
His funeral will be a small family service at St George's Chapel in the grounds of Windsor Castle before the duke is buried in Frogmore Gardens, where Queen Victoria and Prince Albert were laid to rest.
The date has not been set officially, but sources claim it could be on Saturday, April 17.
More details will emerge in the next few days, with the plan nicknamed 'Operation Forth Bridge', but the public have already been urged to stay away to avoid spreading Covid-19 and watch it on TV at home instead.
A state funeral including a flotilla of boats on the Thames to mark his life looks impossible due to covid restrictions, but the Duke was said to have disliked the idea because he 'didn't want the fuss'.
Prince Harry is expected to return to the UK and be among the small number of mourners at the funeral, but it is much less clear whether his pregnant wife Meghan will return, weeks after the couple accused the Royal Family of racism in their bombshell Oprah interview while Philip lay in hospital.
Buckingham Palace announced the death of Prince Philip at just after midday today - and described the Queen's 'deep sorrow'
Philip has served Britain since his youth and the world is mourning his death at Windsor Castle today, with the Royal Family releasing this photo and tribute shortly after his death
Prince Philip waves as he arrives back at Windsor Castle after leaving King Edward VII's Hospital in London on March 16, 2021
Good-looking and blond-haired, the Prince of Greece impressed the young Princess by jumping over the college tennis nets at their first publicised meeting. Pictured: Princess Elizabeth and the Duke of Edinburgh in a wedding photograph in 1947. The couple were married for 73 years (pictured in a portrait taken to mark the 60th anniversary of The Queen's Accession in 2012)
Flags fly at half-mast amid huge outpouring of grief over death of Prince Philip
Flags across the UK are today flying at half mast as the nation remembers the life of Prince Philip after his death was announced by the Queen this morning.
A huge outpouring of grief has seen thousands of tributes online with heartfelt words for Her Majesty - who was described by one well-wisher as having 'lost the brightest jewel in her crown'.
Crowds gathered to carefully place flowers in front of the gates at Buckingham Palace and at Windsor Castle, where notices shared the news of the Duke's passing.
The Duke of Edinburgh's title will eventually pass on to his youngest son, Prince Edward, it was confirmed today - but he will have to wait until after the death of his mother and his brother Charles becomes king because of royal protocols.
The cause of Philip's death has not been made public, but Philip had his first Covid-19 vaccination with the Queen on January 9, with his second one due around a week ago. It is not known if it was administered.
Parliament will be recalled from its Easter recess on Monday - a day earlier than planned - where MPs will give tributes in the Commons.
The Conservatives, Labour and other major parties have suspended campaigning for the local, mayoral and police and crime commissioner elections in May out of respect for the duke.
A frail Philip was last seen leaving hospital on March 16 and his death plunges the nation and the Royal Family into mourning, and brings to an end Philip's lifetime of service to Britain and to Elizabeth, the Queen who adored him since her teens.
The couple shared their 73rd wedding anniversary last November and he was due to turn 100 on June 10 this year.
Boris Johnson led the tributes and addressed the nation outside No 10 Downing Street shortly after the announcement.
He said: 'We give thanks, as a nation and a kingdom, for the extraordinary life and work of Prince Philip, Duke of Edinburgh'.
Boris Johnson spoke outside Downing Street to remember Philip, the love and support he had shown for the Queen and the impact he had on people all over the world
He added: 'Speaking on their golden wedding anniversary, Her Majesty said that our country owed her husband 'a greater debt than he would ever claim or we shall ever know' and I am sure that estimate is correct So we mourn today with Her Majesty The Queen.
'We remember the duke for all of this and above all for his steadfast support for Her Majesty the Queen. Not just as her consort, by her side every day of her reign, but as her husband, her 'strength and stay', of more than 70 years.
'And it is to Her Majesty, and her family, that our nation's thoughts must turn today. Because they have lost not just a much-loved and highly respected public figure, but a devoted husband and a proud and loving father, grandfather and, in recent years, great-grandfather.'
Mr Johnson also praised his Duke of Edinburgh scheme, which has 'shaped and inspired the lives of countless young people'.
Justin Welby, the Archbishop of Canterbury, said: 'As we recover and rebuild after the terrible trial of the coronavirus pandemic, we will need fortitude and a deep sense of commitment to serving others.
'Throughout his life Prince Philip displayed those qualities in abundance, and I pray that we can take inspiration from his example'.
Officials at Buckingham Palace are now preparing for a royal ceremonial funeral at Windsor Castle in Berkshire in keeping with Philip's wishes, with a military procession also expected in London - Covid laws permitting.
Until his death, Philip was the longest-serving consort in British history and the oldest partner of a reigning monarch.
Despite his ill health, the Queen remained resolutely stoic in Prince Philip's final days and took part in her first royal engagement of 2021 last week.
Operation Forth Bridge begins: Queen enters 'eight days of mourning' as master plan for Philip's funeral that the Duke helped draw up himself is enacted but with Covid contingencies for royal ceremonial service and burial in Windsor and military procession
The Queen has entered an eight-day period of mourning following the death of Prince Philip today aged 99 - as arrangements for his funeral, codenamed Operation Forth Bridge, have begun.
The Duke of Edinburgh drew up the plans himself and in character with his no-nonsense attitude will eschew usual state formalities.
Philip will lie at rest in Windsor Castle for a period of days ahead of his funeral at St George’s Chapel, which is expected to be socially distanced.
Royal fans have been told not to attend any part of the events that make up the funeral die to Covid restrictions, or lay flowers.
The Duke of Edinburgh is expected to then be buried in Frogmore Gardens, in the grounds of Windsor Castle.
The Queen will not carry out any duties even in private under Covid restrictions, laws will not be given the Royal Assent and affairs of state will also be paused.
Following these eight days, a further period of official Royal Mourning is expected to continue for 30 days.
Scores of people will be involved in the days ahead, from military guards and the clergy, to staff at Buckingham Palace and Windsor Castle, who will be making sure the household continues to run smoothly during this traumatic time for the Queen.
The Queen and her children and grandchildren will enter a period of mourning for their patriarch, which could last several weeks.
Official engagements, most of which are presently online, can continue during this time, although most are postponed or cancelled, but it depends on the wishes of the monarch.
In non-pandemic times, social engagements would usually be cancelled, except those for charitable causes.
There are various types of mourning, but Royal - also known as Court - Mourning, includes the royal family, royal households and the Queen's representatives in the UK and abroad wearing black and also using black-edged writing paper.