The UK’s mail system is one of the largest in the world and it used by millions of people every day.

Despite this there is still plenty that people do not know about it – from how it began to how changed overtime and even to how it once sponsored children’s TV show.

Here are 9 things you probably didn’t know about one of the UK’s finest institutions.

1. Military might

At the outbreak of the First World War, the Post Office employed more than 250,000 people, making it the largest single employer in the world (it remains the largest in Europe today).

Vast numbers of its staff also signed up for service in the Great War, with 28,000 signed up for the armed forces by the end of 1914. By the end of the conflict, 75,000 staff had been released for war services.

2. Cartoon fun

Royal Mail once sponsored Postman Pat, but stopped that practice in 2000 after claiming the character no longer fitted its corporate image.

3. A public service

The Royal Mail service can trace its roots back to 1516 and the creation of Master of the Posts by Henry VIII – later renamed Postmaster General.

However the service was not made public until July 1635, under the rule of Charles I.

4. Paying for post

Initially the recipient was the one that paid postage fees – a practice that existed until the introduction of the penny black stamp in 1840.

5. Post offices everywhere

At the height of the Post Office’s power in the 1960s there were more than 1,800 Crown offices in the UK.  Now that figure is below 400.

6. Wait for the Bellman

Before letter boxes were introduced to the nation those wanting to send a letter could do so in just two ways – by taking it to a receiving house or by waiting for the Bellman. 

These individuals had a unique uniform and walked the streets collecting letters. As you may guess, they used a bell to attract attention (much like a modern day ice cream van).

7. Where’s the Post Box?

Initial trials for Post Boxes saw them painted green so as to not appear too obtrusive. This plan backfired however, when people reported that they were unable to find them!

Chocolate brown was initially settled on as a replacement colour by the Post Office but as this required an extra coat of varnish it was deemed too expensive. As a result the bright red colour that we know today was adopted.

8. A stamp on time

All stamp designs must be given Royal approval before printing can begin and all commemorative stamps are first considered five years in advance.

It means any stamps you purchase in 2015 probably began life before Fabio Capello’s England side failed so miserably at the South African World Cup and even possibly under Gordon Brown’s labour government – remember him? 

The Olympic Collection meanwhile became the first time that a commercial logo (that of London 2012) had replaced the image of a monarch on regular every-day first class stamps.

9. Underground mail

A rail network under the streets of London transported more than six million bags of mail each year at the peak of operations in the mid 1990s – about four million letters every day.

The concept on underground mail transport was first explored in the middle of the 19th century by the Postmaster General although it took until 1911 before the concept of driverless electronic trains was introduced. Construction began in 1914 and the service ran in some format until 2003 when it was suspended.