[2] The son of Richard Francis Bonner Letts and Jocelyn Elizabeth (née Adami),[3] he was born and raised in Cirencester and for a while attended Oakley Hall Preparatory School, which was run by his father.

He was the first person to write the Mail's pseudonymous Clement Crabbe column, launched in 2006,[6] and has also been the publication's theatre critic since 2004, again at Dacre's suggestion.

[7] Letts was invited to present an edition of the BBC current affairs programme Panorama broadcast on 20 April 2009, which dealt with the growing criticism of the influence of health and safety on various aspects of British life.

[10] 50 People Who Buggered Up Britain has sold around 45,000 copies and was reviewed in The Spectator (a publication Letts writes for) as "an angry book, beautifully written".

Interviewed on the Today programme on BBC Radio 4, he was asked why Paul Dacre, the long-serving editor of one of the best-selling newspapers in Britain (and one of Letts' employers), was absent from the book.

[14] In April 2018, as part of a review of the play The Fantastic Follies of Mrs Rich, an adaptation by the Royal Shakespeare Company of the 18th-century comedy The Beau Deceived by Mary Pix, Letts suggested that actor Leo Wringer was miscast as the nobleman Clerimont.

I suppose its managers are under pressure from the Arts Council to tick inclusiveness boxes, but at some point they are going to have to decide if their core business is drama or social engineering.

In July 2019, in a review of David Hare's production of Peer Gynt at the National Theatre, London, Letts made an unfavourable comparison between English actor Oliver Ford Davies' "fruity purr" to "the whining Scottish accents".

Fellow Scot James McAvoy, though not involved in the production of Peer Gynt, joined the criticism of Letts' remarks, which he called derogatory.

[18] The same paper's theatre critic, Lyn Gardner, observed of a 2007 review by Letts of a stage adaptation for children of Looking for JJ: "I think that this is the first time I've heard of a theatre critic arguing for censorship and demanding that a play should be removed from the stage"; the Daily Mail had been invoked "negatively" in the production.

"[20] Letts was later questioned on these comments by comedian Jo Brand, who was hosting an all-male panel on Have I Got News for You which was aired in 2017 following a House of Commons sexual harassment scandal.

Writing in Church music today '1997 vol 1 p67 he described Sankey and Moody hymns as the greatest contribution to hymnody since Isacc Newton.

On 1 March 2019, the Companies House website published the listing of Letts, his wife Lois and his mother Jocelyn as shareholders (and thus outstanding creditors) of Ffrees Family Finance Ltd, formerly a subdivision of NatWest, for which an administrator was appointed on the same day.