In East and West Sussex flags have been lowered to half-mast, virtual condolence books have been opened, floral tributes laid, and praise for the duke's work in the community have been voiced.
Hundreds of thousands of people have taken to social media to express their sadness at the duke's passing as have many key figures from the UK and around the world, including a number of world leaders.Sussex readers have shared their memories of meeting Prince Philip, including those who received gold Duke of Edinburgh awards and some amusing anecdotes.
Sussex Police & Crime Commissioner Katy Bourne said: “My thoughts and prayers are with Her Majesty The Queen and the royal family at this sad time. HRH Prince Philip was the ultimate public servant and, on behalf of the people of Sussex, I will be writing to send my condolences to the royal household.
“Flags at police headquarters and buildings across our county will be flown at half-mast as a mark of respect for a truly great man.”
Leaders in Chichester, Arun and across West Sussex have joined in with the tributes, with the Dean of Chichester, the Very Reverend Stephen Waine, stating: “His deep love for Her Majesty The Queen has contributed greatly to her long reign, as he supported her constantly in the many challenges which faced her. His sense of duty was beyond compare."
Hastings mayor Cllr Nigel Sinden has laid a floral tribute and opened a virtual condolence book where Hastings residents can leave messages to the Royal family.
A condolence book has also been opened up in Burgess Hill, with the mayor of Burgess Hill stating Prince Philip would be missed for 'his distinctive character and charm'.Eastbourne Borough Council and Lewes District Council have paid tribute to Prince Philip, the Duke of Edinburgh by flying The Union Flag at half-mast. East Sussex MPs took to Twitter with their messages of condolences.
St Catherine's Hospice, which covers West Sussex and East Surrey, said it was very sad to hear the news as Prince Philip was a fantastic supporter of so many charities.
In a statement the hospice said: "Our condolences to Her Majesty The Queen and the Royal Family at this sad time. Our thoughts go out to them and to everyone living with loss and grief right now. HRH The Prince Philip was a fantastic supporter of so many charities, voluntary organisations and the hospice movement."
Public buildings in West Sussex have lowered their flags to half-mast to mark the passing of Prince Philip, including Worthing Fire Station where station commander Roy Barraclough lowered Worthing's flag to half mast this afternoon.
Crawley MP Henry Smith has paid tribute to Prince Philip alongside Crawley Borough Council leader cllr Peter Lamb and Crawley Town Football Club.
Brighton Pavilion's MP Caroline Lucas praised the duke's work in connecting young people with nature and the outdoors via his Duke of Edinburgh awards scheme.
Hove MP Peter Kyle has taken to social media to pay tribute to Prince Philip and share a memory of meeting the Duke of Edinburgh.
Cowdray Park Polo Club and Sussex cricket officials are among many people across the sporting world to pay their respects to the Duke of Edinburgh.
Storrington Parish Council described Prince Philip as ‘much loved and highly respected’.
The duke visited Sussex many times and we have been busy in our newsrooms pulling together a selection of pictures of his visits to the county here. Pictures of Prince Philip visiting Crawley can be seen here.Our entertainments editor Phil Hewitt has reminisced about the time he covered Prince Philip's visit to Worthing - a job that soon became a privilege.
While Worthing’s Taxi Charity has reflected on the day His Royal Highness Prince Philip visited as its guest of honour in 1979.
Prince Philip visited Brighton in October 2016 when the then 95-year-old took a ‘flight’ on and formally opened Brighton’s i360, before meeting its designers and members of the City Council. You can read more about The Duke of Edinburgh's visit to Brighton here.The Queen and Prince Philip has made many visits to the Chichester area, including several to the Roussillon Barracks. You can read more and see pictures of their visits here.The Queen and Prince Philip also visited Horsham twice - in 1978 and 2003. You can read more about the royal visits and see pictures here.How the news broke today
The Royal Family issued the statement on Twitter just after 12pm. In the statement it said: "It is with deep sorrow that Her Majesty The Queen has announced 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."
The Duke of Edinburgh was 99-years-old and was due to celebrate his 100th birthday on June 10.
Prince Philip had spent recent months in hospital. He was first taken in to King Edward VII's Hospital on February 16 as a precaution after feeling unwell. He was then transferred to St Bartholomew's Hospital for continued treatment for a heart condition, before going back to King Edward VII's Hospital. He only left the hospital on March 16.
Prince Philip was the longest-serving consort in British history. The duke and the Queen were married for more than 70 years and Philip dedicated decades of his life to royal duty, serving the nation at the monarch's side.
It is likely Prince Philip will not have a state funeral as he said he did not want 'fuss' so it is likely a ceremonial funeral will take place instead. The Queen is now set to enter an eight day period of mourning.A love story
Prince Philip and Queen Elizabeth met in 1939 when the then Princess Elizabeth was just 13. The couple eventually married in November 1947. You can read more about the royal love story here.Prime Minister Boris Johnson
Prime Minister Boris Johnson said: "It was with great sadness that a short time ago I received word from Buckingham Palace that His Royal Highness The Duke of Edinburgh has passed away at the age of 99.
"Prince Philip earned the affection of generations here in the United Kingdom, across the Commonwealth and around the world. He was the longest serving consort in history, one of the last surviving people in this country to have served in the second world war at Cape Matapan, where he was mentioned in despatches for bravery and in the invasion of Sicily, where he saved his ship by his quick thinking and from that conflict he took an ethic of service that he applied throughout the unprecedented changes of the post war era.
"Like the expert carriage driver that he was he helped to steer the royal family and the monarchy so that it remains an institution indisputably vital to the balance and happiness of our national life.
"He was an environmentalist, and a champion of the natural world long before it was fashionable. With his Duke of Edinburgh awards scheme he shaped and inspired the lives of countless young people and at literally tens of thousands of events he fostered their hopes and encouraged their ambitions.
"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.
"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 offer our condolences to her and to all her family and we give thanks, as a nation and a Kingdom, for the extraordinary life and work of Prince Philip, Duke of Edinburgh."