DESIGNED BY BENJAMIN Wyatt (1775-1852) and George Louch, then later modified by John Rennie (1761-1821), The Clock House (built 1817) overlooks the harbour in Ramsgate, Kent. As its name suggests, this building is surmounted by a square tower with clocks on each of its four sides. Today, the time on the clocks is Greenwich Mean Time (‘GMT’) or, when appropriate, British Summer Time (GMT+1). But this has not always been the case.

The Clock House was home to chronometers that were used to synchronise shipborne chronometers employed for determining longitude. The edifice stood on what was known as the Ramsgate Meridian Line, which was established in 1819. This was before 1851 when Sir George Airy (1801-1892) defined the position of the prime meridian that runs through the observatory at Greenwich. It was not until 1884 that the prime meridian at Greenwich was recognised internationally, much to the disgust of the French, who hoped it would run through Paris.

The now disused Ramsgate Meridian Line is east of the Greenwich prime meridian. So, when the clocks on the Clock House were set to Ramsgate Mean time, they were 5 minutes and 41 seconds ahead of GMT. A notice beneath the clock tower informs the viewer that the clocks are now set to show the same time as it is in Greenwich. And if there are any ancient mariners still using Ramsgate Mean Time, they are informed by another notice that:

“Ramsgate Mean Time is 5 min 41 sec faster than this clock.”

Whichever time you choose to use, it is well worth spending some hours, if not longer, in Ramsgate, which is full of interesting things to see as well as the Clock House.