Following the death of Her Majesty The Queen, all official flags, including the Union Flag, should be half-masted from as soon as possible today until 08.00 the day following The Queen’s State Funeral. Flags may be flown overnight during this period but should remain at half-mast.
Official flags in this instance are defined as national flags of the home nations, Crown Dependencies and Overseas Territories, Ensigns and Ships’ colours.
Any non-official flags flying or due to be flown, such as the Rainbow Flag or the Armed Forces Day Flag, should be taken down and replaced with a Union Flag at half-mast. Other official flags scheduled to be flown can be flown as normal, but at half-mast.
Half-mast means the flag is flown a third of the way down the flagpole from the top, with at least the height of the flag between the top of the flag and the top of the flagpole.
On poles that are more than 45° from the vertical, flags cannot be flown at half-mast and should not be flown at all.
Thank you to the Maritime Authority of the Cayman Islands for this information.