"The first pillar boxes in Britain were introduced in the Channel Islands as an experiment in 1852. Anthony Trollope, the novelist, who was employed by the General Post Office, trialled pillar boxes in the Channel Islands before introducing them into mainland Britain. He was influenced by roadside letter-receiving pillars used in France. Before the use of pillar boxes, on the mainland, individual letters would be taken by hand to a letter receiving house or post office, which was often a coaching inn, a postage stamp purchased and the letter handed to the receiver or postmaster, to connect with the mail coach and later the railway. In the Channel Islands, people took their letters to the mail steamer when it was awaiting the tide in the harbour – the particular problem of an island mail service then. Pillar boxes allowed letters to be posted at any time and they could then be collected when a steamer was due. They were convenient and immediately successful. However, as with many innovations, the first boxes were introduced into Jersey. One of these original pillar boxes can be seen in Union Street, St Peter Port and has been maintained by Guernsey Post in its traditional red livery."
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Apart from the original number one post box, all the Guernsey post boxes started to be painted blue from 1st October 1980.