The second of the Astute Class submarines to be built at Barrow in Cumbria has been officially named.
About 2,000 people attended the ceremony at BAE System's yard, performed by the wife of the Royal Navy's Commander in Chief.
The company said a technical problem with heavy moving equipment meant the submarine could not be hoisted on to a special ceremonial platform.
The submarine will begin sea trials in about a year's time.
The vessel, which weighs approximately 7,200 tonnes, is armed with Spearfish torpedoes and Tomahawk Land Attack Missiles.
A BAE Systems spokesman said: "A last minute technical issue with some of the equipment used to move the submarine prevented it from being moved to its ceremonial position.
"There is no issue whatsoever with the submarine itself and the ceremony took place as scheduled within the Devonshire Dock Hall.
"Ambush is now planned to move out of the hall in the coming days."
The submarine produces its own air and water, so can circumnavigate the globe without needing to surface.