City of Westminster in Greater London, England, United Kingdom — Northwestern Europe (the British Isles)

Sir Ambrose Fleming

Photographed by Andrew Ruppenstein, April 23, 2026

1. Sir Ambrose Fleming Marker

Inscription.
Sir Ambrose Fleming
1849-1945

Scientist and Electrical Engineer

lived here

Erected 1971 by Greater London Council.

Topics. This historical marker is listed in this topic list: Science & Medicine. A significant historical date for this entry is December 12, 1901.

Location. 51° 31.426′ N, 0° 10.967′ W. Marker is in City of Westminster, England, in Greater London. It is on Clifton Gardens east of Warwick Avenue, on the right when traveling east. Touch for map. Marker is at or near this postal address: 9 Clifton Gardens, City of Westminster, England W9, United Kingdom. Touch for directions.

Regionally, this marker is in the Greater South East.

Globally, it is on the Atlantic Ocean,

in the North Atlantic Region,

in Europe,

in Atlantic Europe,

on one of the British Isles,

in the Western World,

and in the Anglosphere.

Historically, it finds itself in what was once the Roman Empire.

Other nearby markers. At least 8 other markers are within walking distance of this marker: Alan Turing (about 120 meters away, measured in a direct line); Marc Bolan (about 150 meters away); John Masefield (about 240 meters away); Jackie Forster (about 240 meters away); Sir Lennox Berkeley (approx. 0.3 kilometers away); Little Venice (approx. 0.3 kilometers away); Grand Union Canal (approx. 0.3 kilometers away); Little Venice: a place to be (approx. 0.3 kilometers away). Touch for a list and map of all markers in City of Westminster.

Also see . . . John Ambrose Fleming (Wikipedia). Excerpt:

Sir John Ambrose Fleming (29 November 1849 – 18 April 1945) was a British electrical engineer and physicist.
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He is known for inventing the vacuum tube radio transmitter — with which the first transatlantic radio transmission was made—and establishing the right-hand rule used in physics.

Radio transmitter: In 1899, Guglielmo Marconi, the inventor of radiotelegraphy, decided to attempt transatlantic radio communication. This would require a scale-up in power from the small 200–400 watt transmitters he had used up to then. Marconi contracted Fleming, an expert in power engineering, to design a radio transmitter. He designed the world's first large radio transmitter, a complicated spark transmitter powered by a 25 kW alternator driven by a combustion engine—built at Poldhu, Cornwall—which transmitted the first radio transmission across the Atlantic on 12 December 1901.

Fleming valve: In 1904, while working for the Marconi Company to improve transatlantic radio reception, Fleming built the first vacuum tube—the two-electrode diode—which he called the "oscillation valve", for which he received a patent on 16 November. It became known as the Fleming valve. The Supreme Court of the United States later invalidated the patent because of an improper disclaimer and, additionally, maintained the technology in the patent was known art when filed.

This invention of the vacuum tube is often considered to have been the beginning of electronics. Fleming's diode was used
Photographed by Andrew Ruppenstein, April 23, 2026

2. Sir Ambrose Fleming Marker - wide view
in radio receivers and radar for many decades afterwards, until it was superseded by solid-state electronic technology more than 50 years later.

(Submitted on April 29, 2026.)

Additional keywords. blue plaque

Credits. This page was last revised on April 29, 2026. It was originally submitted on April 29, 2026, by Andrew Ruppenstein of Lamorinda, California. This page has been viewed 5 times since then. Photos: 1, 2. submitted on April 29, 2026, by Andrew Ruppenstein of Lamorinda, California.