I am not sure of the significance of this phone box and can only assume it is to do with the era of the style:- The K6 was commissioned in 1935 to commemorate the silver jubilee of King George V. The design of the "Jubilee Kiosk" needed to be good, so Sir Giles Gilbert Scott was again drafted in to design the new kiosk. The K6 was similar to his K2, but was smaller and had simpler detailing, but was still unmistakably a Gilbert Scott design and would be a success. It appeared in 1936, followed by a more vandal-proof Mk2 in 1939; by 1960 some 60,000 examples existed. The Post Office allowed rural examples to be in different colours; so for example green, yellow, white and battleship grey examples exist. Red was initially chosen so as to stand out in case one needed to make an emergency call.