Tremlett is a Visiting Fellow of the Cañada Blanch Centre at the London School of Economics and is author of four works of history and non-fiction that have been translated into half a dozen languages. He won the Elizabeth Longford Prize for Historical Biography in 2018. For the past 20 years, he has held various roles for The Guardian, where he now mostly contributes Op-Eds and long form international reportage. He previously worked for The Economist.
He had his first taste of Spanish life when he lived in Barcelona for two years in the mid eighties. After a period in Lisbon and then in London, he returned to live in Spain in the mid-1990s. He was The Guardian's correspondent for Spain, Portugal and the Maghreb for a dozen years. He was also Madrid correspondent for The Economist for a decade until 2016. In 2012 he was voted Correspondent of the Year by the Madrid International Press Club. He has been a regular current affairs commentator for Spanish broadcasters, including state-owned TVE television, La Sexta and the country's biggest radio station, Cadena SER, as well as writing for newspapers like El País or El Mundo. He was co-founder and curator of the Docubeats documentary project at The Guardian and El País.
He has been a guest lecturer on journalism or contemporary Spanish history and participant in seminars at numerous universities, including Oxford, MIT and Stanford.
Tremlett is a twin. He moved around the world from an early age, following his father Colonel Edward Tremlett to postings in South Africa, Tanzania, Kenya, Turkey and Germany. He currently[when?] lives in Madrid with his wife and two sons.
His book Ghosts of Spain: Travels through a country's hidden past (2007) was translated into five languages and has sold 150,000 copies worldwide.
In 2010 he published a biography of Catherine of Aragon, the Spanish infanta who became Henry VIII's first wife, with Faber and Faber in London and Walker in New York. Catherine of Aragon was BBC Radio 4's "Book of the Week" and was short-listed for the HW Fisher Best First Biography Prize. It has been translated into Spanish, Russian and Polish.
His biography of Isabella of Castile – the Spanish queen who sent Columbus to the Americas - was published in 2017. It won the Elizabeth Longford Prize in 2018. It was one of the best-selling history books in Spain in 2018 and has also been translated into Portuguese and Chinese.
In October 2020 he published The International Brigades: Fascism, Freedom and the Spanish Civil War, which was a Guardian newspaper "book of the Day". It draws on archive material held in Moscow and recently made available to historians. Reviews in historiographic periodicals have not been published yet, but according to the historian Sir Paul Preston, it provides "in lucid and compelling prose, the overall history of the Brigades that has been lacking". In popular media opinions differ from generally favorable though warning that the volume might seem "overly sympathetic to the Brigades", to enthusiastic notes that "this book is as close to a definitive history as we are likely to get".
- Ghosts of Spain Faber and Faber. ISBN 978-0-571-22169-1
- Catherine of Aragon Walker & Company. ISBN 978-0-8027-7916-8
- Isabella of Castile Bloomsbury ISBN 978-1408853979
- The International Brigades: Fascism, Freedom and the Spanish Civil War Bloomsbury ISBN 978-1408854006
- "Giles Tremlett". Sobirania i justícia. Retrieved 10 November 2017.
- Profile of Giles Tremlett. www.theguardian.com
- Larman (2017). "Isabella of Castile by Giles Tremlett review – she fought and conquered". Retrieved 2018-06-23.
- "Giles Tremlett wins". The Bookseller. 2018. Retrieved 13 August 2018.
- Richard Baxell, How the International Brigades were ‘thrown into the heart of the fire, [in:] The Spectator October 17, 2020
- Dan Hancox, The International Brigades by Giles Tremlett review – fighting fascism in Spain, [in:] The Guardian October 3, 2020
- "Archived copy". Archived from the original on 2011-07-26. Retrieved 2010-05-26.CS1 maint: archived copy as title (link)