In an unbroken series traced back to the Norman Conquest and before, the Great Seal of the Realm has provided the means by which the will of the sovereign can be expressed. Styled the clavis regni, or key of government, it is such an important instrument of state that, in centuries past, the counterfeiting of it was an offence of high treason punishable by death.

The last 1,000 years may have witnessed extraordinary political, economic and social changes but still, the position of the Seal at the heart of government is as fundamental in the twenty-first century as it was in the eleventh. Its meaning remains virtually unchanged and, just as occurred in the reign of Edward the Confessor, impressions taken from the Seal are appended to a variety of official documents in order to signify royal assent.

The Great Seal itself consists of a pair of silver moulds, or matrices, into which designs have been engraved: cakes of softened wax, or in more recent times a plastic compound, together with a set of strings are placed between the upper and lower matrix and pressure applied to make a double-sided impression which can then be attached to a document using the loose ends of the strings. Only one Great Seal is in use at any given time and in a long reign, the silver matrices eventually wear out; Queen Victoria, for instance, had four different Great Seals during the 63 years of her reign. When a new Seal is prepared, the old Seal is ceremonially defaced and is then by custom presented by the Monarch to the Lord Chancellor of the day. The matrices of the Queen's first Great Seal were therefore presented to Lord Irvine as a personal gift.