The first standard public telephone kiosk, introduced by the United Kingdom Post Office, was produced in concrete in 1920 and was designated K1 (Kiosk No.1).
The red telephone box was the result of a competition in 1924 to design a kiosk that would be acceptable to the London Metropolitan Boroughs which had resisted the Post Office's effort to erect K1 kiosks on their streets.
The Post Office chose to make Scott's winning design in cast iron (Scott had suggested mild steel) and to paint it red (Scott had suggested silver, with a "greeny-blue" interior) and, with other minor changes of detail, it was brought into service as the Kiosk No.2 or K2. From 1926 K2 was deployed in and around London.
The red phone box evolved in the form of K3-5 but the K6 is last, and by far the most widespread model used.
The K6 was designed in 1935 to commemorate the silver jubilee of King George V. K6 was the first red telephone kiosk to be used extensively outside of London, and many thousands were deployed in virtually every town and city, replacing most of the existing kiosks and establishing thousands of new sites. It has become a British icon, although it was not universally loved at the start. The red colour caused particular local difficulties and there were many requests for less visible colours.
In 1952 the new Queen, Elizabeth II, decided to depart from the practice of using the purely symbolic 'Tudor Crown' as the symbol of her government, and instead use a representation of the actual crown generally used for British coronations, the St Edward's Crown. This new symbol therefore began to appear on the fascias of K6 kiosks.
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