Emergency diversion route (square)

This sign means: Symbols showing emergency diversion route for motorway and other main road traffic. It is a direction sign: it gives information about your route, not an order.

Official Highway Code caption: “Symbols showing emergency diversion route for motorway and other main road traffic.”

Listed under “Other direction signs” in The Highway Code: traffic signs (GOV.UK). For every sign in more detail, see the Department for Transport’s Know your traffic signs.