John L. Holmes was born in North London, United Kingdom, the son of a civil servant and a stay-at-home mother. From an early age, Holmes was encouraged to read, write and experiment. World War II disrupted his education, when the pupils of the Westcroft School were evacuated from London to the West Country, but by Christmas 1939 Holmes had returned to London to be with his parents. He remained in London for the duration of the war, and vividly recalls the London Blitz.

A mere ‘pass’ in chemistry on his Higher School examination meant that Holmes was bound for employment, rather than university. He accepted a position as a trainee analytical chemist at Glaxo Laboratories, where he learned to assay penicillin samples and to devise new analytical methods for novel synthetic products. While working at Glaxo, he pursued his education one day and three evenings per week at Acton Technical College, eventually passing the London External BSc examination in chemistry. His score earned him admission to graduate studies at University College London. There he studied thermal decomposition of alkyl iodides under the mentorship of Allan Maccoll.

After earning his PhD, Holmes fulfilled his National Service requirement at the National Coal Board then took up a postdoc in Ottawa at the National Research Council (NRC) of Canada, doing photochemistry of trifluoromethyl radicals with aromatic substrates. It was at NRC that he met Fred Lossing and got his introduction to mass spectrometry. After a frustrating two-year interlude at the University of Edinburgh, Holmes returned to Ottawa, accepting a position as assistant professor in the Chemistry Department at the University of Ottawa, where (with the exception of sabbaticals and visiting professorships abroad) he spent the remainder of his career. He began his work at Ottawa on the kinetics of hydrogen atom reactions, but soon found himself volunteering to take on a leadership role in the department’s nascent center for mass spectrometry. Throughout the interview, Holmes recounts his evolving research interests, his collaborations with Fred Lossing, Hans Terlouw and others, his teaching and mentoring work, as well as the changing funding climate in Canada, the growth of the University of Ottawa, his experiences at international scientific meetings, and his work as editor of Organic Mass Spectrometry. Holmes concludes the interview with a discussion of his passion for sailing.