The Mace in the House of Commons was originally the emblem of office of the Serjeant at Arms, but it has become the symbol of the power and privileges of the House. In medieval days, maces were weapons of war, being used to belabour your armour-clad opponent once you had both been unhorsed.

The House cannot be properly in session without the mace. It is carried by the Serjeant at Arms before the Speaker in procession to prayers, which opens each sitting of the House, and is carried out by the Serjeant when the House rises each night. When the House is sitting, with the Speaker or Deputy Speaker in the chair, the mace rests on the Table of the House. When the House goes into Committee (ie undertakes detailed examination of a Bill), the Speaker leaves the Chair, and the Serjeant places the Mace on two supports below the Table.

The present Mace dates from the reign of George III, but was probably made up from the pieces of two maces which were made at the Restoration of the Monarchy in 1660. (The cap, with its royal arms with the Garter and the motto 'Dieu et mon Droit', bears the initials 'CR', presumably for Charles II.) It is silver gilt and measures 4ft 10ins, that is 1.4 m in length, with an overall weight of 16 lb or 7.2 kg. The head is divided into four panels which contain a crowned rose, a thistle, a harp and a fleur-de-lis, the whole being surmounted by a royal crown with orb and cross. The shaft, consisting of one short and two long sections, is covered with branches from which roses and thistle flowers spring.