GMT adopted in Britain Before 1850, almost every town in Britain kept its own local time, based on solar time. Therefore, there were no standard times established for when the day would begin and end. For example, there was Greenwich Mean Time (GMT) as well as a Bristol Mean Time (10 minutes behind GMT) and Cardiff Mean Time (13 minutes behind GMT). This was especially problematic for the railways. It was the expansion of the railways that finally compelled authorities to establish a standardised time throughout the country. To ensure the smooth and timely running of trains, the railways started using a single standard time on their timetables, which was mostly GMT. In December 1847, GMT was adopted by the Railway Clearing House and was officially known as Railway Time. Although most of the clocks in Britain were set to GMT by 1855, the adoption of GMT was not official until the Statutes (Definition of Time) Act (43 & 44 Vict.) was passed and legally adopted throughout Great Britain on 2 August 1880. Image Credit GNR 4-2-2 No.1 (Stirling Single) - 1980. Object number: 1975-7014/1 Science Museum Group Collection © The Board of Trustees of the Science Museum, CC BY-NC-SA 4.0, https://collection.sciencemuseumgroup.org.uk/objects/co8352583/great-northern-railway-locomotive-stirling-single-steam-locomotive
