When should the Union flag be flown at half mast?

Flags At Half Mast Over London (1941)

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

Union flags fly at half mast in tribute to the late Duke of Edinburgh | SWNS

How to fly a flag at half mast

Union Jack Flags flying at Half Mast

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

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

Union Jack, British Flag 🇬🇧

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

Peterborough Flying Flag Half-Mast After The Queen Dies

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

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

Flying the Union Jack at half-mast

EU flags at half mast following attacks

Half Staff Flags Explained | Flag Facts

Flags fly at half-mast at British embassies

Flag is flying at half-mast 21 December, 2022

How To Fly a Flag At Half-Mast Correctly on a Wall Mounted Flagpole 🇬🇧

Flag at half-mast over the UK parliament