Before it was destroyed by bombing during World War 2, Exeter City Library once housed an interesting clock which had two large minute hands. One indicated Exeter Local Time, the other Greenwich Mean Time. Exeter Local Time was officially 14 minutes 12 seconds slow of GMT (Greenwich Mean Time).
This discrepancy had mattered little in the days before railway travel but once rail networks began to create timetables covering the country it was soon clear that there was a requirement for time to be standardised.
In 1852, a telegraph line was competed linking Greenwich Observatory with London. Shepherd's Electro-Magnetic Clock was installed at the Observatory specifically for the transmission of Greenwich Mean Time to distant places. The first transmissions were to London Bridge Station. Large, conspicuous clocks began appearing at major railway stations so that travellers could be in no doubt that the trains on that line were running at what was known as "London Time". People had become very attached to their own "local" times however and for a long period many public clocks had two minute hands - one showing London (or more correctly, Greenwich, Time the other showing Local Time.
For reasons that varied from place to place, there was considerable delay in getting this simple idea accepted across the nation. There were many public meetings and much discussion in the local press before GMT became universally accepted in the UK. It was not until 1st June 1880 that the Definition of Time Bill, was read for the first time in the House of Commons. It received the Royal Assent on 2nd August 1880 and only then was there a "standard" time in use across the whole of Britain, removing all the confusion caused by local times.
Clocks on the Royal Estate at Sandringham only finally came into line in 1936, having been kept 30 minutes ahead of GMT to allow King Edward VII more daylight time for shooting - his favourite sport.