To mark the passing of His Royal Highness The Prince Philip, Duke of Edinburgh flags should be flown at half-mast until 08:00 hrs on the morning after the Funeral.
Half-mast means the flag is flown two-thirds of the way up the flagpole, with at least the height of the flag between the top of the flag and the top of the flagpole. Flags cannot be flown at half-mast on poles that are more than 45° from the vertical, but a mourning cravat can be used instead (see the Flag Institute’s website for further details). When a flag is to be flown at half-mast, it should first be raised all the way to the top of the mast, allowed to remain there for a second and then be lowered to the half-mast position. When it is being lowered from half-mast, it should again be raised to the top of the mast for a second before being fully lowered. When a British national flag is at half-mast, other flags on the same stand of poles should also be at half-mast or should not be flown at all. Flags of foreign nations should not be flown, unless their country is also observing mourning.