A writ in acceleration, commonly called a writ of acceleration, was a type of writ of summons that enabled the eldest son and heir apparent of a peer with multiple peerage titles to attend the British or Irish House of Lords, using one of his father's subsidiary titles. This procedure could be used to lower the average age of the house, and increase the number of capable members in a house that drew on a very small pool of talent (a few dozen families in its early centuries, a few hundred in its later centuries), without increasing the effective size of the peerage and thereby diluting the exclusivity of noble titles.