After working for a number of New Zealand and Australian publications during the 1960s, Gibbard moved to London and was initially employed by The Daily Telegraph before joining The Guardian in 1969, replacing Bill Papas.
[3] Responding to the sinking of General Belgrano, on 6 May 1982 the newspaper ran Gibbard's version of the cartoon, re-captioned with the line: "The price of sovereignty has increased - official".
The cartoon was raised in the House of Commons and was cited as evidence, by the then Prime Minister Margaret Thatcher that the British media did not support military action, and rival newspaper The Sun also accused Gibbard and The Guardian of treason: "What is it but treason for The Guardian to print a cartoon, showing a British seaman clinging to a raft ... isn't that exactly calculated to weaken Britain's resolve at a time when lives have been lost, whatever the justice of her cause?"
He also provided illustrations for the popular New Zealand social commentary book, The Half Gallon Quarter Acre Pavlova Paradise.
He has also contributed to a number of international animated features including The Super Globetrotters, Under Milk Wood and Ivor the Invisible.