Today (25 July 2019) Highway Code rule 258 has been updated to provide details about red ‘x’ signs on motorways. The amends are: Red flashing lights. If red lights flash on a signal and a red “X” is showing, you MUST NOT drive in the lane shown as closed beyond the signal. This applies until you pass another signal indicating that the lane is no longer closed, by displaying the word “End” or a speed limit sign and you are sure that it is safe to proceed. Red flashing lights. If red lights flash on a signal in the central reservation or on the side of the road and lane closed sign is showing, you MUST NOT go beyond the signal in any lane.