Why the DVLA adds five onto the driving licence numbers of millions of Brits

Your driving licence number is one of those strings of digits and letters through which the government identifies you. Like a passport or National Insurance number, for many of us, it is just another random code to remember - but those 16 characters are anything but random.

Located on the front of the photocard licence, this unique collection of letters and number is what you use when applying for car insurance, or paying the DVLA for speeding fines. The first five letters are usually the same as the start of your surname, but if your surname is less than five characters a nine is added - making a Mr Lee's licence read LEE99, followed by 11 letters and numbers.

Men looking at their driving licence might spot that some of the numbers that follow are the same as their date of birth but in a scrambled order. However, women might not be able to spot this so easily as the DVLA adds a "gender marker" to their licence number.

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This section of the 16-character code after the first five letters of your surname splits the DD/MM/YY format into a scrambled Y/MM/DD/Y layout, and adds a five onto the month of your birth if you are a woman.

This means the licence of a man called Mr Johnson, born February 3 1991, would start to read JOHNS902031. While a woman born on the same date called Ms Johnson would have a licence reading JOHNS952031.

This is the only indication of gender that is part of your driving licence by default, though your title of address could also indicate this. Trans women who want to have their identity recognised on their licence in the same way can also apply to have this gender marker on their licence number