G1 HJK
These are the style of registrations used between August 1983 and 2001. These consist of: 1 letter, up to 3 numbers and then 3 letters.
ABC 199
This type of registration was issued for new vehicles prior to February 1963. These consist of three letters followed by three numbers.
AB12 CDE
These are the style of registrations currently issued to new vehicles in mainland GB. These consist of: 2 letters, 2 numbers and then 3 letters.