WHERE would we be without postcodes today? It’s impossible to fill out an online form without one, your home insurance cost depends on it, and all you need is a postcode and a house number for a delivery to find its way to the right spot.

And as long as we have the postcode we are (almost!) sure to get to the right place thanks to Google Maps and the like.

But what I was surprised to learn from my dad’s October 16, 1976, column is that postcodes only achieved nationwide coverage relatively recently.

He talks of direction signs near Milton Keynes, a “new town in the south of England”, that included the postcodes of that area. He goes on, “It is like saying l live in YO6 4DX instead of Ampleforth, for I understand the post office can identify a precise building by the new postal code system”.

Dad was irritated that the local council was considering assigning numbers to all the houses in the area to make life easier for the postal and emergency services.

He loved having a house with a name rather than a number, a privilege that many people living in rural communities enjoyed, and our home had a beautiful plaque on its façade proudly declaring “Coram Cottage” which dad lovingly repainted most years.

“I wonder if these changes were a deliberate ploy by this Government to reduce our individually styled rural havens into featureless piles of equally-shaped bricks?” he grumbled.

He needn’t have worried as our cottage, and many other houses in the village, never received a number, and when in the early 1980s we moved to a newly-built house in the same village, it too had a name rather than a number (to this day, delivery drivers have trouble finding it, although locals will point them in the right direction).

London was the first place to trial postcodes in 1857 when the city was divided into 10 postal districts, many of which still stand today. However, a couple were later allocated to other districts (NE to Newcastle and S to Sheffield).

Once it was deemed a success, the system spread further afield, with Liverpool being the first to follow suit in 1864, and Manchester close behind.

It wasn’t until 1959 that the modern system began to be used, with the introduction of sorting machines.

Norwich was selected to try it out, with 150,000 addresses assigned postcodes that began with the letters “NOR”, followed by two digits and another letter, although it was later changed to “NR”.

Then in 1965, when Tony Benn was Postmaster General, he extended the system to the whole of the UK in an eight-year programme, starting in urban areas then fanning out to the more rural parts of the country. This explains why Dad was still referring to it as the “new postal code system” in 1976.

Over time the term “postal code” was shortened and by 1984, as my Concise Oxford English Dictionary of that date tells me, it was hyphenated to “post-code”. In the current OED it’s one word, “postcode”.

In today’s postcodes, the first two letters indicate the nearest large town or city, of which there are 124 in Britain.

The number which follows represents a postal district in that area and this first half of the code is known as the “outward” code, indicting which sorting office the item of mail needs to be sent to.

The second half of the code is called the “inward” code, and the first number shows which “sector” the letter should go to (there about 9,500 sectors in the country).

The final two digits refer to a specific street or area, accounting for roughly 17 homes. Obviously these numbers change regularly as the population increases and fresh postcodes are assigned to new buildings.

Royal Mail has a useful webpage explaining how to correctly address an envelope whether writing it by hand, or printing an address label.

It doesn’t overtly state that there has to be a space between the two halves of the postcode, and these days many online forms omit it, but in the Royal Mail illustration, there is a clear gap.

Other tips include to preferably use black ink, write neatly in the centre of the envelope but with all text aligned from the left. And (this one I didn’t know for sure) no commas at the end of each line of the address.