He was born Julius Gottheimer in Dalston, London, Middlesex, England UK, the son of David Gottheimer and Minnie Mikah Gottheimer, and brother to Solomon Gottheimer. In 1926, he married "Lena" Levy (dec. 1956), raising a son and a daughter, followed later by a second marriage.
Grant made a career exposing forgeries on the basis of chemical analysis of paper, ink and other characteristics of written documents. Much of his work was for British Intelligence as illustrated in the Colin Wallace Clockwork Orange investigation. Well into retirement, Grant was called in to investigate possible forgery and to give expert evidence in court. In 1984 Grant's analysis of the Hitler Diaries confirmed within a week that it was a forgery. He was also called as a witness in the war-crimes trial of John Demjanjuk.
Grant lived for many of his later years on Friday Island one of the islands in the River Thames. The lock keeper at Old Windsor Lock nearby recalled Dr Grant saying that when he went to the island, he felt it was like going a million miles away. It was like owning half of Australia, it was so secluded.
In the fictionalized 'autobiography' of a former serving officer of Her Majesty's Intelligence Service, "Friends" Secret Intelligence Service MI6, the novelist, convicted fraudster  and Zionist agent, Michael John O'Hara (aka Zeev Gideon Korwan), wrote "Julius Grant to me and indeed to many law enforcement officers worldwide was arguably the world's most respected forensic scientist in his particular area of expertise. I liked the man personally and he I".
- Marco Fontani, et al., The Lost Elements: The Periodic Table's Shadow Side (Oxford University Press, 2014) p. 349
- Julius Grant (Gottheimer)
- The Telegraph Obituaries: Dr. Julius Grant
- BBC 25 April 1983: 'Hitler diaries' published
- New York Times War-Crimes Trial, Horror and Humdrum December 13, 1987
- Paul Goldsack River Thames: In the footsteps of the famous English Heritage/Bradt 2003
- O'Hara v The Secretary of State for Education and Skills (2007) EWCST 858(PT) (21 August 2007)
- Michael John O'Hara, "Friends" Secret Intelligence Service MI6 An Autobiography (Lulu, 2006) ISBN 184728678X OCLC 226973822