When should the Union flag be flown at half mast?

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

Half Staff Flags Explained | Flag Facts

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

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

Union Flag at half-mast.

Downing Street Union Jack 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

When to Fly the US Flag at Half Staff

Flags At Half Mast Over London (1941)

Why The Union Jack Is On The Hawaiian Flag #hawaii #flag #history #vexillology #flagfacts

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

Union Jack at half mast at the Tower of London and bell being tolled 96 times on Fri 9th Sept 2022

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

American regions that still have a Union Jack 🇬🇧

EU flags at half mast at the Berlaymont building following the passing of Queen Elizabeth II

EU flags placed at half-mast across the European Union following the passing of Queen Elizabeth II

History flag in England 🏴󠁧󠁢󠁥󠁮󠁧󠁿 @UnitedWhiteFlag @officialenglandcricket

EU flag sales in UK at half mast after Brexit vote

The Union flag flying at half mast at the local Church, due to the recent passing of the Queen.