Greenwich Mean Time: What Time Is It, Anyway?

For much of history, people weren’t very concerned about the exact time. As they went about their everyday lives, it just didn’t make that much difference. They could approximate the time by the position of the sun, and that was close enough.

Then mechanical clocks appeared in Europe during the 11thcentury. These new timepieces could tell the time even on cloudy days or at night. When big clocks began to be installed in public squares for all to see, they often had only an hour hand. That was good enough for most people in the time before everyone planned their days in 15 minute increments.


Life was going along smoothly with everyone having a vague idea what time it was until the railroads came along. By the mid-1800s, train tracks were running all over the UK. But there was one a little hiccup. Since every town operated on solar time, setting their clocks by the sun, it was a slightly different time in every town. This made train timetables next to impossible to create or follow. So the Great Western Railway decided that all their trains would run on London time (Greenwich time).

The clock on the old Corn Exchange in Bristol, UK. The thicker minute hand is Bristol time and the thinner one is Greenwich Time.

That was an improvement, but each town still kept its own time. That meant that outside the train station it might be 5:00 but inside, it might be 5:15. This problem was “solved” by installing clocks with two minute hands: one for railroad time and one for local time. It was confusing, and many people missed their trains.

If this was a problem in the UK, it caused chaos in the vast expanse of the United States. One US time table showed the top 100 or so major cities and what time it was there when it was 12.00 noon in Washington D.C. With this information, the passengers were instructed to calculate the difference between two cities to work out the local time. 

In case you can’t read the instructions at the bottom of the time table, they say:

“By an easy calculation, the difference in time between the several places above named may be ascertained. Thus, for instance, the difference of time between New York and Cincinnati may be ascertained by simple comparison, that of the first having the Washington noon at 12.12 P.M., and of the latter at 11.31 A.M.; and hence the difference is 43 minutes, or, in other words, the noon at New York will be 11.17 A.M. at Cincinnati, and the noon at Cincinnati will be 12.43 P.M. at New York. Remember that places West are “slower” in time than those East and vice versa.”

Easy peasy, right?

Back in the UK, the General Post Office began to transmit the time from the Royal Observatory in Greenwich to towns throughout the country. They did this by way of the newly invented electronic telegraph. Soon thereafter, most of the towns in the UK decided to make life easier and set their clocks to Greenwich time. Greenwich Mean Time became the norm, but it wasn’t until 1890 that it became law and all of the UK was officially on the same time. 

Synchronizing the World

By 1870 many countries had recognized the need for standardized time. The first International Geographical Congress was held in Antwerp in 1871. The Greenwich Meridian was approved for use on certain navigational charts. Then in 1876 a Canadian man, Sandford Fleming, came up with a novel idea. Why not pick one longitude, call it Longitude 0 and set time all zones from there. He proposed the Greenwich Meridian.

Put It to a Vote

In 1884 US President Chester A. Arthur called for an International Meridian Conference to be held in Washington D.C. Participating nations would decide on a meridian to be designated as Longitude 0. From there, a standard time system for the entire world could be established.

Twenty-five nations participated in the conference. The motion to designate the Greenwich Meridian as Longitude 0 passed 22-1. Only the Dominican Republic voted against it. France and Brazil abstained. It seemed that the rivalry between the UK and France was still alive and well. 

France argued that the location of the Longitude 0 should be a neutral location – not based in any major country. Of course, the problem with that was that there needed to be an observatory on the meridian, and the observatory needed to be on land. 

But Why Greenwich?

Greenwich had a lot going for it. First of all, there was already an observatory there. Then there was the fact that the UK was a world shipping power. All its ships had been using Greenwich Mean Time since 1825, and most sea navigation charts used by other countries were based on GMT too. So nearly everyone saw it as the logical choice. The Greenwich Meridian was designated as Longitude 0 and time zones would be established from there.

The French weren’t thrilled about this. Perhaps they were still smarting from their several defeats at the hands of the British Navy. Anyway, France didn’t accept Greenwich Mean Time until 1911, 86 years later. They went by Paris Mean Time which was 9 minutes and 21 seconds earlier than GMT. But, eventually, France joined the rest of the world’s time system. 

In 1967 the official International designation for Greenwich Mean Time became UTC. This abbreviation is the result of a compromise: The British wanted CUT (Coordinated Universal Time) and the French wanted TUC (Temps Universel Coordonné). So they just mixed up the letters and came up with UTC. But in many English-speaking countries, it’s still referred to as Greenwich Mean Time.

Some countries (like France) took a while to get on board, but now most of the world calculates time from Greenwich Mean Time… I mean Coordinated Universal Time. 

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Margo Lestz
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  1. Another very interesting research Margo. I was amazed that the time in Britain was not standardised until 1890 and the rest of the world did not agree to 0 longitude until the end of the 19th Century. And, the difficulties in achieving this. Fascinating!
    Many thanks

    1. Thanks, Paula. It’s hard to believe that there was a time when nobody really cared what time it was. It must have been a much slower-paced life.

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