Born in Cranfield, Bedfordshire during World War II, he was educated by the Christian Brothers in Bristol, and at the University of London where he studied English. He lives in London with his wife and they have two sons.

Cronin is a television and stage actor, particularly remembered for his role as PE teacher 'Bullet' Baxter in the television series Grange Hill between 1979 and 1986. He also appeared in Fawlty Towers as Irish cowboy builder Murphy (who Manuel memorably called a "hideous orangutan"). He has appeared in episodes of Foyle's War, Midsomer Murders, The Sweeney and Bergerac. In 1990 he played Alfred Inglethorp in the Agatha Christie's Poirot film The Mysterious Affair at Styles, and played Sergei in the 2000 television adaptation of Anna Karenina. He has also appeared in the British television programme, Merlin (2008), as the character Geoffrey of Monmouth.Other television work includes: The Sweeney, Marie Curie, Chinese Puzzle, Midnight at the Starlight, Invasion, Tiny Revolutions, The Gentle Touch, Glorious Day, Bergerac,  The Bill, Wycliffe, Tom Jones, Shakespeare Shorts, Our Mutual Friend, Goodnight Mr Tom, The Mayor of Casterbridge and the BBC series, Merlin.

His theatre work includes: An Empty Desk (Royal Court); Duet for One, Hamlet, Due Process of Law ( Dukes, Lancaster); Hamlet, Jail Diary of Albie Sachs, and Gloo Joo ( Young Vic); Hedda Gabler (Octagon, Bolton); Caesar and Cleopatra, The Prisoner of Zenda, and The Corn is Green ( Greenwich Theatre). From 1986 to 1991 he worked with the English Shakespeare Company in Richard II, Henry IV Pts 1 and 2, Henry V, Henry VI, Richard III, Coriolanus , and The Winter's Tale, and toured with them in the UK, Europe, Japan, USA, India and Australia; All My Sons ( Oxford Stage Company/ Wolsey); Purcell's The Indian Queen with the King's Consort and NYMT at the Queen Elizabeth Hall and Schwetzingen Festival in Germany;  Hamlet, and, Comedians (The Belgrade, Coventry);  Northanger Abbey (Greenwich Theatre); The Merchant of Venice (Salisbury Playhouse); Timon of Athens (AJTC Brix Theatre) The Taming of the Shrew , Don Juan  The Masterbuilder ,The Cherry Orchard, Love’s Labour’s Lost, Ghosts, King Lear,  Romeo and Juliet, Twelfth Night, (English Touring Theatre) Mary Stuart (Derby Playhouse) Richard II (Steven Berkoff) Hamlet, Mother Courage (English Touring Theatre); The Last Confession (Chichester/The Haymarket London).

His film work includes: Jesus of Nazareth, Hopscotch, Oliver Twist, The Captive, Hour of the Pig, Heart of Darkness, The Grotesque, For My Baby, Jeremiah,  RKO 281, The Discovery of Heaven, The Wolfman.

Michael Cronin has written three children's novels, published by Oxford University Press. His first novel, Against the Day, was short listed for the 1999 Angus Book Award. The story is set after the end of Second World War in an England that has fallen under Nazi occupation. It follows the adventures of two boys who become dangerously involved in a secret resistance movement. A sequel, Through the Night, was published in 2003. A third book in the series, In the Morning, was published in 2005.

He is also a screenwriter with two film screenplays to his credit.

Bibliography

• Against The Day - 1998 novel (ISBN 0-19-275267-7)
• Through the Night - 2003 novel (ISBN 0-19-275221-9)
• In The Morning - 2005 novel (ISBN 0-19-275447-5)

• No Final Truth - film script
• Stealing the Fire - film script