When ordering the abandonment on the Victor (and presumably also Valiant and Vulcan which had the same set up) the command was "Emergency parachute, jump, jump". We three down the back did not have ejection seats of course and had to jump for it, before (hopefully) the two pilots banged out, presumably without any further command from the captain. All I know is that given the poor survival rate for rear crew abandonments on V Aircraft I am very pleased never to have put the procedure into practice.