A mathematics graduate from St John's College, Cambridge during World War II, Marriott was quickly sent in 1943 to Bletchley Park, then the United Kingdom's main codebreaking establishment.
[2] A Stamp collector from the age of twelve,[3] Marriott was a specialist in Trinidad postal history.
Apart from new issues sent by postal administrations, Marriott bought "errors, freaks, and oddities" : stamps with missing colours or inverted picture for example.
[2] He retired from teaching in 1982 and was elected to serve as president of the Royal Philatelic Society London (RPSL) from 1983 until 1986.
[2] Facing an increasing amount of work and activities, he was the first keeper of the Royal Collection to have a deputy: Charles Wyndham Goodwyn, president of the RPSL since 1991.