A new submarine built by BAE systems in Cumbria left Barrow-in-Furness at the weekend to begin sea trials.

The Astute sub is due to go into full service next year but will first undergo 18 months of rigorous testing by the Royal Navy.

It is the biggest nuclear attack submarine ever built and is armed with more torpedoes and missiles than any previous British vessels.

Advanced technology will ensure that the sub never needs to be refuelled. It will also be able to circumnavigate the entire globe while submerged.

Defence equipment and support minister Quentin Davies said the Astute class of submarines will "deliver a step change in capability for defence in terms of anti-submarine and anti-surface warfare".

The completion of the vessel represents a major success for Cumbria's engineering industry.

Barrow-in-Furness has been producing submarines for more than 100 years. All of the country's Vanguard class vessels were manufactured in the northwest town.