The mace is a silver gilt ornamental club of about five feet in length, dating from the reign of Charles II.
It symbolises the royal authority by which Parliament meets and also the authority of the Speaker.
On each day that the House is sitting the mace is carried to the chamber at the head of the Speaker's procession by the Serjeant at Arms.
It is placed on the table of the House, except when the House is in committee, when it rests on two brackets underneath the table.
Interfering with the mace constitutes gross disorderly conduct and is a contempt of the House.
Heseltine wields the mace
Michael Heseltine famously seized the mace after a particularly heated debate in 1976.
The evening of 27 May proved to be a particularly eventful one for the House of Commons.
The government was attempting to steer its Aircraft and Shipbuilding Industries Bill through the Commons.
The Bill was hotly contested, with Michael Heseltine leading the Conservative opposition. The vote on an amendment had been tied, and was lost on the Speaker's vote. The vote on the main government motion - which one would have expected also to be tied - was in fact carried by the Labour Government.
At this, some of the Welsh Labour MPs began to sing 'The Red Flag'. Heseltine, infuriated by the traditional Labour Party anthem, grabbed the mace and held it over his head.
He was restrained by Jim Prior, replaced the mace and left the Chamber. The Speaker suspended the sitting until the following day.
The next morning Michael Heseltine apologised unreservedly for his behaviour.