When transatlantic services began in the 1840s, people had rarely travelled such a long distance so regularly. On arriving at a British port, it would take American sailors time to get used to the fact that their onboard clock was around five hours behind local time. Similarly, people travelling to America from Britain would appear to lose five hours. At this point, Britain had only just achieved a standard time throughout the country - previously, towns would have had their own 'local time'.

Time difference would not become a notable problem for transatlantic travellers until the era of supersonic air travel aboard Concorde, when it would be possible to arrive in America at an earlier time than leaving Britain. However, it did matter when calculating journey time for BlueRiband attempts - Greenwich Mean (London) Time is used throughout. Otherwise, it would be possible for westbound ships to record the local time of departure from Britain and the local time of arrival in New York and appear to cut five hours off the time of their voyage.

Some of Cunard's early voyage record books for ships sailing between Liverpool and Halifax, Canada show time differences of anything between three and seven hours. In a famous case of 1902, a transatlantic crossing record attempt by Norddeutcher Lloyd vessel Kronprinz Wilhelm was disallowed because the ship's captain had incorrectly calculated the journey time.

Across the great divide

There and back again

Time difference

Transatlantic milestones