Prefix style registrations, also known as private number plates, were introduced by the DVLA in August 1983. They use the structure A*BBB, where A is a letter which represents the period that the vehicle was first registered, and * is a 1-3 digit number. This style is the reverse of its predecessor the Suffix style, which follows the format BBB*A. Private number plates cannot incorporate the letters I, Q or Z; O and U can only appear in the last three letters.

Prefix style registrations were initially released annually and were issued between 1st August and 31st July of each year. This changed with the introduction of the T-registrations on 1st March 1999, which started the bi-annual release of registrations in the periods 1st March - 31st August, and 1st September - 28th February.

Private number plates lend themselves perfectly to initials or short words, for example D24AWN, G50RGE or M321GAN. For those who want to emphasise their names, they can choose shorter registrations such as M21LEE, or H6VRM. It also allows for combinations such as M155XXC (Miss) or K155ESS (Kiss), H20UBR (H2O for plumbers) and for some more unusual eye-catching registrations like T31SLX.