Michael Gambon as John Harrison

Jeremy Irons as Rupert Gould

Ian Hart as William Harrison (Adult)

Andrew Scott as John Campbell

Bill Nighy as Lord Sandwich

Gemma Jones as Elizabeth Harrison

John Wood as Sir Edmund Halley

Anna Chancellor as Muriel Gould

Brian Cox as Lord Morton

Samuel West as Nevil Maskelyne

Ian McNeice as Dr. Bliss

Jonathan Coy as Adm. Sir Cloudsley Shovell

Christopher Hodsol as Capt. Ainsley

Liam Jennings as William Harrison (Young)

Peter Vaughan as George Graham

Nigel Davenport as Sir Charles Pelham

Tim McInnerny as Christopher Irwin

John Standing as Capt. Proctor

Peter Cartwright as Army Doctor

Stephen Fry as Sir Kenelm Digby

Daragh O'Malley as Capt. Bourke

Cliff Parisi as Lt. Draper

Michael Cochrane as Waddington, Gould's solicitor

Tobias Menzies as Halley's Secretary

Charles Edwards as Lt. Seward

Pip Torrens as Capt. Lindsay

T. P. McKenna as Edmund Burke

Barbara Leigh-Hunt as Dodo Gould

Peter-Hugo Daly as John Jefferies

John Normington as Mr. Greene

Nicholas Rowe as King George

Roger Lloyd Pack as Capt. Man

Trevor Cooper as Roger Wills

Lucy Akhurst as Grace Ingram

Peter Penry-Jones as Surgeon

Mark Tandy as Whiston

Heike Makatsch as Queen Charlotte

William Thomas as Arthur Mason