The observatory grounds overlie to the south the site of the former Sheen Priory, the Carthusian monastery established by King Henry V in 1414.

[6] Co-Observer The observatory was completed in 1769,[8] in time for King George III's observation of the transit of Venus that occurred on 3 June in that year.

The geomagnetic instruments had already been relocated to Eskdalemuir Observatory in Dumfries and Galloway, Scotland in 1908 after the advent of electrification in London led to interference with their operations.

[12] A contemporary report by Stephen Demainbray, the superintendent of the observatory, says: "His Majesty the King who made his observation with a Shorts reflecting telescope, magnifying Diameters 170 Times, was the first to view the Penumbra of Venus touching the Edge of the Sun's Disk.

The network of observing stations set-up in 1867 by the Met Office to assist in understanding the weather was equipped with his cameras – some of these remained in use at Kew until the observatory's closure in 1980.

[15] Ronalds also established a sophisticated atmospheric electricity observing system at Kew with a long copper rod protruding through the dome of the observatory and a suite of novel electrometers and electrographs to manually record the data.

He supplied this equipment to facilities in England, Spain, France, Italy, India (Colaba and Trivandrum) and the Arctic with the goal of delineating atmospheric electricity on a global scale.

A secondary system of measurement, operating on different principles, was designed and implemented by the Nobel laureate CTR Wilson, from which records begin in 1906 until the closure of the Observatory.

[19] In the early 1850s, the facility began performing a role in assessing and rating barometers, thermometers, chronometers, watches, sextants and other scientific instruments for accuracy; this duty was transferred to the National Physical Laboratory in 1910.

[21] In 2014 Richmond upon Thames London Borough Council granted planning permission for the observatory to be used as a private single family dwelling.

The entrance octagon room originally would have housed George III's scientific instruments but displays the owners collection of Japanese ceramics and has an upper gallery installed by the Met Office with an Art Deco balustrade.

The lounge has been restored as a Georgian room with two large portraits of George III and Queen Charlotte and a decorated modern carving of his coat of arms.

The dining room is decorated with modern, hand-painted Chinese wallpaper, based on the 1772 painting commissioned by Alexander Hume, now in the Hong Kong Maritime Museum.