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John St. Vincent Pletts (1880-1924) of Marconi's Wireless Telegraph Co
1924 Obituary 
JOHN ST. VINCENT PLETTS was born at Ryde, Isle of Wight, on 22nd January 1880, and was educated at the Isle of Wight College and at the Central Technical College of the City and Guilds of London Institute, obtaining the Diploma.
From 1899 to 1905 he was employed by Marconi's Wireless Telegraph Co., Ltd., in charge of erecting and installing work in America, Africa, Russia, and the Far East. In 1906 he was appointed Deputy Chief of Staff of the Company and held this post until 1910, when he became head of the Company's Patent Department.
During the War he was engaged at the War Office as expert in Cryptography.
After the Armistice he returned to the Marconi Company as consulting engineer in connexion with patent and legal work.
His death took place at Surbiton on 26th April 1924, at the age of forty-four.
He became a Member of this Institution in 1920.
1924 Obituary 
JOHN ST. VINCENT PLETTS was born on the 22nd January, 1880, and died at his home at Surbiton on the 26th April, 1924, after a short illness.
He received his general education at the Isle of Wight College and in 1896 went to the Central Technical College, in the department of electrical engineering, where he stayed for three years.
He then joined the Marconi Wireless Telegraph Co. and was engaged in erecting wireless stations for the company in Hawaii, Labrador, the Congo, Russia and the Far East.
From 1910 until 1919 he was head of the company's patent department. In the capacity of consulting engineer he was their expert in all legal cases on patents relating to wireless telegraphy, including the well-known "7777" case and the "Mullard valve" case.
He was a member of various technical societies and a writer of technical articles, in addition to being the inventor of a slide rule and a cryptograph machine. During the war he acted as expert in cryptography at the War Office. He was a very reserved man and, though holding a prominent position, was very unostentatious and considerate towards those who worked for him.
He was elected an Associate of the Institution in 1902 and a Member in 1919.