NUCLEAR-POWERED submarine HMS Astute returned to the River Clyde yesterday after a 142 day deployment to America.

The mighty 7,800-tonne vessel was away for its most important series of sea trials yet - and came through with flying colours.

During the deployment she 'battled' against USS New Mexico, America's newest and best Virginia class hunter attack submarine, deep dived, fired her Tomahawk Land Attack Missiles and sailed 16,400 miles.

Commanding Officer Iain Breckenridge, 45, was met in the Clyde by his wife, Steph and she sailed with him the last few miles to the Coulport side of HM Naval Base Clyde.

He said: "We are looking forward now to a bright future - this is a submarine of tremendous capability.

"We met and surpassed every expectation, she is better than any other submarine I have ever been on.

"She is still on trial and she is first of class, which always brings its own problems, but we are beginning to look beyond those problems and see the promise.

"We fired off four Tomahawks, aimed at a corner of Eglin Air Force Base to test for accuracy and we fired six Spearfish torpedoes, including the first salvo firing by a British submarine for 15 years.

"Our sonar is fantastic and I have never before experienced holding a submarine at the range we were holding USS New Mexico. "The Americans were utterly taken aback, blown away with what they were seeing." The 318ft-long Astute will never need to be refuelled and her sonar can track ships 3,000 miles away.

Her missiles have a target range of 1,200 miles with accuracy measured in metres.

Naval command in Britain can reprogramme the missiles in mid-flight even if the submarine is thousands of miles away.

Next in line for Astute is a base maintenance period at HM Naval Base Clyde before returning to sea later in the year for more trials.