He has been a guest lecturer on journalism or contemporary Spanish history and participant in seminars at numerous universities, including Oxford, MIT and Stanford.
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.
Catherine of Aragon was BBC Radio 4's "Book of the Week" and was short-listed for the HW Fisher Best First Biography Prize.
[citation needed] In October 2020 he published The International Brigades: Fascism, Freedom and the Spanish Civil War, which was a Guardian newspaper "book of the Day".
[citation needed] In popular media opinions differ from generally favourable though warning that the volume might seem "overly sympathetic to the Brigades",[6] to the statement that "this book is as close to a definitive history as we are likely to get".