This comes from the website of the Department for Culture, Media and Sport.
Half-masting instructions
It is with great regret that we learn of the death of the King Abdullah bin Abdulaziz, King of Saudi Arabia.
It is requested that all flags be half-masted from 8am today until 8pm this evening.
Any other UK national flags flown alongside the Union Flag when it is at half-mast should also be at half-mast. If a flag of a foreign nation is normally flown on the same stand as the Union Flag, it should be removed.
Local authorities are not bound by this request but may wish to follow it for guidance. Devolved administrations are responsible for issuing instructions for the flying of the Union Flag on buildings in their estate and others as necessary.
Not in my name, thanks! If Saudi Arabia didn't have all that oil we would be treating it as a rogue state. A state that can sentence a man to 1000 lashes for simply expressing an opinion isn't fit to be treated as a civilized country.