By August 2017, he is a two-time Combined Services Senior Boxing champion and had an amateur record of 23 wins, 11 of which are by knockouts, and 11 losses.

Marvin is the first Filipino with foreign heritage absorbed to the Philippine national team since Christopher Camat, who competed at the 2004 Summer Olympics.

[2] He went to Guangzhou in July 2017 to train with his countrymen along with Chinese, Kazakh, and South Korean boxers before competing at the 2017 Southeast Asian Games.

[2] Marvin was born to John Sr., a British retired professional singer, former cruise director and a yacht master, and Teresita Tupas, a Filipina who is native to Pampanga.

[3] in January 2021 he appeared before the Isle of Wight magistrates court and was given a suspended sentence and convicted of ABH and beating up women.