Saluting batteries began firing 41 rounds at one round every minute from midday on Saturday in cities including London, Edinburgh, Cardiff and Belfast, as well from Royal Navy warships.
Ships taking part included HMS Diamond, HMS Montrose and HMNB Portsmouth, while the Royal Gibraltar Regiment joined the salute from the British overseas territory, the Ministry of Defence said.
The public were encouraged to observe the gun salutes, which are fired to mark significant national events, on television or online, rather than gathering in crowds to watch outside.
“His Royal Highness leaves us with a legacy of indomitable spirit, steadfastness and an unshakeable sense of duty,” said General Nick Carter, chief of the U.K. Defense Staff.
“From all of us who serve today and who have served, thank you.”
In London, the King’s Troop, Royal Horse Artillery, fired 36 horse-drawn guns at a parade ground in Woolwich Barracks.
Edward and the Countess of Wessex spent around an hour at the castle and Sophie told reporters “the Queen has been amazing” as they left Windsor in a Land Rover.
Prince Charles stayed with the Queen until late last night.
The Duke of Edinburgh’s coffin is in a private chapel of worship.
Details of the duke’s funeral - which will take pace next Saturday 17 April - were revealed today.
Just 30 people will attend in line with Covid-19 restrictions.