A writ of acceleration was granted only if the peerage being accelerated was a subsidiary one, and not the father’s highest, and if the beneficiary of the writ was the heir apparent of the actual holder of the peerages; thus, the elder peer was always at least a viscount. The heir apparent was not always summoned in his courtesy title; rather, almost every person summoned to Parliament by virtue of a writ of acceleration was summoned in one of his father's baronies. For example, William Cavendish, Marquess of Hartington, heir apparent of William Cavendish, 3rd Duke of Devonshire, was summoned as "Baron Cavendish of Hardwick". It was not possible for heirs apparent of peers in the Peerage of Scotland and Peerage of Ireland to be given writs of acceleration after 1707 and 1801, respectively, as holders of titles in these peerages were not automatically guaranteed a seat in the Westminster House of Lords.