No vehicles over maximum gross weight shown

This sign means: No vehicles over maximum gross weight shown (in tonnes). It is a sign giving orders, which you must obey. Signs with red circles are mostly prohibitive, and a plate below a sign qualifies its message.

Official Highway Code caption: “No vehicles over maximum gross weight shown (in tonnes).”

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