When should the Union flag be flown at half mast?

Downing Street Union Jack at half-mast after death of Queen Elizabeth II | AFP

Flags At Half Mast Over London (1941)

The Union Jack flag at Whitehall is flown at half mast following the death of Queen Elizabeth II.

Why Do We Fly Flags Half Mast or at Half-Staff?

Union Jack Flags flying at Half Mast

Half Staff Flags Explained | Flag Facts

When should the flag be flown at half staff?

Union Jack at Buckingham Palace at half-mast after death of Queen Elizabeth II

Union Jack 🇬🇧 half mast at Brompton-on- Swale church

users have claimed that Union Flags are flying at half-mast outside

Union Jack at Buckingham Palace at half-mast after death of Queen Elizabeth II | AFP

U.S. lawmakers honor Queen Elizabeth II, flags fly at half-staff

the Union Jack Still flies on our flag

American regions that still have a Union Jack 🇬🇧

Are Union Flags flying at half-mast across UK? As netizens worry for Kate and Charles

Union Jack flags @ halfmast

Flying the Union Jack at half-mast

Union Jack, British Flag 🇬🇧

Union flags at half mast across the UK 🇬🇧🌗