It was in 1857 when, faced with London’s ever-burgeoning population, Sir Rowland Hill, inventor of the postage stamp, introduced a scheme to accelerate mail delivery. This divided the capital into 10 separate postal districts - N, S, E, W, NE, NW, SE, SW, EC and WC. The public were then asked to add these district letters to the bottom of addresses.

The system of postcodes that we know today was rolled out in the 1960s. There are now in excess of 1.7 million postcodes across the UK, covering 27 million addresses. Postcoded letters can be read by Royal Mail’s machinery and sorted 30 times faster than by hand.

Today, 98% of all mail includes the postcode, keeping Royal Mail’s delivery system running smoothly and efficiently. They are also the backbone for many services, such as online shopping and satellite navigation systems. Even so, one in six items of non-business mail omits the postcode.

Jennie Longden, Head of Royal Mail’s Address Management team, said: "The history of the postcode may stretch back 150 years, but it’s still as important today as it ever was to help Royal Mail sort and deliver mail quickly and efficiently. I’m delighted to see that so many people take the time to check their postcode via Royal Mail’s website. By taking care with addressing and always using the postcode, people can help us to ensure their cards and letters arrive safely.

Did you know?
• Royal Mail’s online postcode checker gets around 4.5 million hits per month - equivalent to 55 million checks per year

• Santa Claus has his own special postcode - SAN TA1 - and gets 750,000 letters every year to his North Pole address

• Some famous addresses have their own postcode - Albert Square in Eastenders (E20), Coronation Street (M10) and Ambridge, home to the Archers (AM1)