WHERE ARE YOU? WHAT'S THE TIME?

How the world's clocks and geographic coordinates came to be set by a small borough of London

- WORDS BEN BIGGS

Telling the time used to be a lot more complicated than it is now. Today we have 24 one-hour time zones set across the world, and if we move west or east, crossing from one zone to another, we know to set our watches and phones back or forward an hour. But 200 years ago in Britain, before digital timepieces existed, when wristwatches were the preserve of the wealthy and most people told the time by the gong of a church bell or even a sundial, we had local time. The time differences between cities and major settlements were a matter of minutes. For example, Plymouth is around 180 miles west of Greenwich in London, so clocks on the Devon border city were 16 minutes and 30 seconds behind those in Greenwich. This didn't matter much, because travel between cities was very slow and only a few travellers owned portable timepieces that required adjusting. But the advent of fast railways replaced horse and cart, so by the mid-19th century, varying local mean times at each train station could get quite confusing.

In 1828, clock maker Benjamin Lewis Vulliamy pushed for public clocks across London, which all showed different times, to be set by the clock on St Paul's Cathedral. And in 1845, railway businessman Henry Booth put a petition before parliament arguing that all public clocks in the country should be set by St Paul's. When an electric clock was installed in the Royal Observatory Greenwich in 1852, which connected to train stations via telegram wires, it allowed all public clocks in the country to be set by the Royal Observatory Greenwich, establishing Greenwich Mean Time.