The origins of this macabre device are medieval, although the date of its earliest use remains uncertain.
An early record comes from Halifax in West Yorkshire, which had the right to execute criminals by 1280 at the latest. A machine called ‘The Halifax Gibbet’ was first recorded as being used there in 1286 when one John Dalton was beheaded.
A 16th-century engraving entitled The Execution of Murcod Ballagh Near to Merton in Ireland 1307 shows a similar machine suggesting these were also in use in medieval Ireland. Scotland, not wishing to be left out, employed the ‘Maiden’, based on the Halifax Gibbet, to lop the heads off criminals from around the minority of James VI until its abolition c1710.
Joseph Guillotin merely recommended the use of this fairly common execution engine to the French National Assembly when on a committee chaired by Dr Antoine Louis, which had been given the task of suggesting a practical execution device. They took their inspiration from the Halifax Gibbet and an Italian machine known as the Mannaia, as Louis states in his report to the Comité de Législation.
The first actual guillotine was probably built by the German harpsichord maker Tobias Schmidt and was first used on 25 April 1792. The term ‘guillotine’ was first recorded in print by the journalist Louis René Quentin de Richebourg de Champcenetz who, ironically, was also to become one of its victims.
Answered by Justin Pollard, author of Secret Britain: the Hidden Bits of Our History (John Murray, 2009). He is a question writer for the panel show QI on BBC One.