Shrapnel was born in Birmingham, Warwickshire, the son of Mary Lillian Myfanwy (née Edwards) and journalist/author Norman Shrapnel.
Shrapnel was educated at the City of London School, an independent school for boys in the City of London, and Mile End School, Stockport where he was first involved in acting as a member of the school's drama society, followed by St Catharine's College, Cambridge, where he obtained an M.A..
As a stage actor, Shrapnel was a member of Laurence Olivier's National Theatre Company and the Royal Shakespeare Company and most recently appeared as Sir Oliver Surface in The School for Scandal (directed by Deborah Warner) at the Barbican Centre in 2011. He Narrated the Episode on Wild Discovery.
Shrapnel has also appeared extensively on television in roles in Elizabeth R, Z-Cars, Edward and Mrs. Simpson, Space: 1999, Inspector Morse, GBH, Coogan's Run and Foyle's War. He presented an episode of the 1983 BBC television travel series Great Little Railways. He gave performances in three entries in the BBC Television Shakespeare plays and as Creon in the BBC's productions of the Three Theban plays (1986) of Sophocles. He also played Pompey in the second episode of Ancient Rome: The Rise and Fall of an Empire and the Jail Warden in The 10th Kingdom, an epic fantasy miniseries.
His film career has included roles in Nicholas and Alexandra (1971), Pope Joan (1972), Hennessy (1975), Personal Services (1987), Testimony (1988), How to Get Ahead in Advertising (1989), England, My England (1995), 101 Dalmatians (1996), Notting Hill (1999), The Body (2001), K-19: The Widowmaker (2002) and Alien Autopsy (2006). He has also appeared in historical films such as Gladiator (2000) as Senator Gaius, Troy (2004) as Nestor, Elizabeth: The Golden Age (2007) as Lord Howard and The Duchess (2008) as General Grey.
Shrapnel has the rare distinction of appearing in two episodes of Midsomer Murders as two different characters, in Death in Chorus and Written in Blood. Shrapnel appeared in an episode of Jonathan Creek as Professor Lance Graumann in the episode The Omega Man. He appears in Chemical Wedding alongside Simon Callow, telling the tale of the resurrection of occultist Aleister Crowley.
Shrapnel also has experience in the field of BBC radio drama: He has played Colin Dexter's Inspector Morse (opposite Robert Glenister as Sgt. Lewis) and has starred in William Gibson's Neuromancer.
Shrapnel is the son-in-law of British film actress Deborah Kerr, through his 1975 marriage to her younger daughter Francesca Ann Bartley. They have three sons, the actors Lex Shrapnel (b. 1979) and Tom Shrapnel (b. 1981), and the writer Joe Shrapnel (b. 1976). They live in Highbury, north London.
Shrapnel played the character Deputy Assistant Commissioner John Felsham in the New Tricks episode The Fourth Man (2010). DAC Felsham is exposed as having been involved in criminal conspiracy, and he is arrested and escorted from the premises in the final moments of this episode.