This article investigates the history of the Labour Party's National Executive Committee. It argues that the party's trade unions, outside a brief period of left‐wing NEC control between 1972 and 1981, formed a Praetorian Guard at the Executive around the party leader from Labour's foundation until 1997, and have continued to serve in an enlarged Praetorian Guard since then. From 1900–97, the unions maintained effective control of over half of the NEC's seats. Although widespread changes to the Executive in 1997 shifted the unions into a minority on the Committee, they continued to guard the leader. However, following the election of Jeremy Corbyn in 2015, factional disputes led to a breakdown of the Praetorian Guard during heated battles for control of the NEC. Since this period, it is argued, Labour leaders have built new guards in which the unions continue to serve, but which also include soldiers from across the labour movement.