Im wrong - not the first time certainly wont be the last time...
Diplomatic plates
British diplomatic car plate.
See also: List of country codes on British diplomatic vehicle registration plates
Since 1979 cars operated by foreign embassies, high commissions, consular staff, and various international organisations have been given plates with a distinguishing format of three numbers, one letter, three numbers. The letter is D for diplomats or X for accredited non-diplomatic staff. The first group of three numbers identifies the country or organisation to whom the plate has been issued, the second group of three numbers is a serial number, starting at 101 for diplomats (although some embassies were erroneously issued 100), 400 for non-diplomatic staff of international organisations, and 700 for consular staff. Thus, for example, 101 D 101 identifies the first plate allocated to the Afghan embassy, 900 X 400 is the first plate allocated to the Commonwealth Secretariat.
101 D 101 101 D 101
900 X 400 900 X 400
A limited number of "personal" plates, bearing a similar format to earlier civilian registrations, are issued to embassies and high commissions for use of their ambassador or high commissioner. For example, the United States embassy is allowed to use the registration USA 1 on one of its fleet of vehicles; Zimbabwe's high commissioner has ZIM 1 and South Korea's ambassador ROK 1 - 'Republic of Korea'. The North Korean embassy, however, had to buy a vanity plate: PRK 1D .[46]