This portrait of Oliver Cromwell shows him being prepared for battle by a page, who attaches an identifying coloured sash to his left arm. He holds a military baton, a symbol of command. Cromwell, Member of Parliament for Huntingdon and Cambridge, was one of the Parliamentary leaders during the English Civil War and supported the execution of Charles I in 1649. Prior to the Restoration of Charles II in 1660 Cromwell held power as Lord Protector until his death. The painting is said to have come with the Cottonian collection which was given to the nation in 1700 but its date of 1725 seems to indicate that it is a later acquisition. The Cotton collection was transferred to the British Museum in 1753.

The portrait is thought to come from the studio of Robert Walker and is similar, but not identical, to a portrait of Cromwell by this artist transferred to the National Portrait Gallery from the Museum in 1879.