The craze for purchasing private number plates in the UK is pretty high. Though the choice of a personalised number plate in the UK is quite restricted in comparison to other countries around the world. Registration plates in the UK follow a unique system where the age of the vehicle along with the area of registration is followed by some random numbers.
But for personalised number plates, UK car registration formats only allow up to three letters to appear consecutively without being intervened by a number. So a little improvisation is actually required to have names and words displayed on the private number plate in the UK. This is achieved by innovatively combining actual letters with numbers that represent letters. Hence, you will see several number plates with K on the end.
Original Source: https://www.quora.com/Whats-with-UK-private-number-plates-that-have-a-short-number-followed-by-K/answer/Leicester-Motor