A set of four stamps issued by the British Post Office to celebrate 100 years of Greenwich mean time. From bottom left are a 28p stamp depicting the Greenwich Observatory, which houses collections of timekeeping and navigational instruments; a 16p stamp showing a photograph of the Earth taken by Apollo 11 astronauts on their pioneer flight to the Moon; a stamp showing a navigational chart of the English Channel; and a 31p stamp depicting the transit telescope designed and installed by Sir George Airy, the Astronomer Royal, in 1850. The telescope is still in working order. All the stamps feature the Prime Meridian which is represented by a red line. The meridian was selected at a conference in Washington D.C. in 1884, when Greenwich was chosen from among 25 countries as the world-wide base for measuring time and longitude at sea, in the air, and in space.

Press, 21 June 1984, Page 16

A set of four stamps issued by the British Post Office to celebrate 100 years of Greenwich mean time. From bottom left are a 28p stamp depicting the Greenwich Observatory, which houses collections of timekeeping and navigational instruments; a 16p stamp showing a photograph of the Earth taken by Apollo 11 astronauts on their pioneer flight to the Moon; a stamp showing a navigational chart of the English Channel; and a 31p stamp depicting the transit telescope designed and installed by Sir George Airy, the Astronomer Royal, in 1850. The telescope is still in working order. All the stamps feature the Prime Meridian which is represented by a red line. The meridian was selected at a conference in Washington D.C. in 1884, when Greenwich was chosen from among 25 countries as the world-wide base for measuring time and longitude at sea, in the air, and in space.