It is an offence to fail to comply with traffic signs.
The maximum penalties are:
It is no defence that the driver failed to see the sign. No intention to fail to comply is necessary (see Hill -v- Baxter  1 All ER 193). A mechanical defect of which the driver was unaware, may amount to a defence (see R -v- Spurge  2 All ER 688), as will the loss of control over the vehicle due to circumstances beyond the control of the driver (see Burns -v- Bidder  3 All ER 29).