Maunsell was born in 1884 in
Srinagar,
Kashmir in
British India, one of three children of a military family. His father, Edward Henry Maunsell (1837–1913) was of
Anglo-Irish ancestry, and was a
captain in the
5th Dragoon Guards and
15th Hussars. His mother, Rosalie Harriet Anson (1852–1922), was born in
Guernsey; the couple had married in
Bombay Cathedral in 1878. He was related distantly to General Sir
Frederick Richard Maunsell (1828–1916) of the Royal Bengal Engineers. Young Guy was sent to school in England at
Eastbourne College between 1897 and 1903, and studied
civil engineering at the Central Institution of the
City & Guilds of London Institute, South Kensington. Although he graduated with first class honours in 1906, he did not find immediate employment and travelled the country making
watercolour paintings. The next year, he became an assistant to Swiss engineer
Adrien Palaz (1863–1930), professor of Industrial Electricity at the
University of Lausanne, where he learned the latest techniques associated with
reinforced concrete. In 1909 he secured a job with
Easton Gibb & Son who were engaged in the construction of the
Rosyth Dockyard. In July 1914, Maunsell moved to
R. Thorburn and Sons as their chief agent and was responsible for building two
TNT factories for the British Government. ==World War I==