It's been around a while, but still funny.

Announcement made jointly by the DVLA and DSA, Tuesday 15 June 2004 at
10:00 BST.

Driver & Vehicle Licensing Agency DVLA Press Office, Longview
Road, Morriston, Swansea SA6 7JL. Telephone: 01792 782318. E-mail:
press.dvla@gtnet.gov.uk

Driving Standards Agency Stanley House, 56 Talbot
Street, Nottingham NG1 5GU. Telephone: 0115 901 2500. Fax: 0115 901
2510.

In order to assist other motorists in identifying potentially
dangerous drivers, it is now compulsory for anyone with low driving
ability to display a warning flag.

The flag (comprised of a red cross on a white background) will be
attached to the top of at least one door of their vehicle.

For drivers of exceptionally low ability, additional flags are
required.