From the first cut of steel in 1999 to its maiden voyage 10 years later, construction of HMS Astute has been an enormous undertaking, a series of demanding tasks that a dedicated workforce approached with both pride and vigour.

At 97 metres long and displacing 7,400 tonnes, its size is matched only by the scale of operation required to turn the many thousands of detailed designs into the finished article.

Almost every inch of the 170-acre Barrow shipyard, and its sister sites in Ash Vale, Weymouth, Farnborough, Waterlooville and Filton, have been utilised at some stage to piece together this ultimate underwater weapon.

The Devonshire Dock Hall (DDH) stands proud as the main build facility, the last destination in Astute’s construction journey before she underwent final test and commissioning in the adjacent Devonshire Dock waters.

It was within the towering walls of the cavernous DDH building that Astute went from being a series of hollow, cylindrical units to the magnificent first of class submarine we see today.

As the construction process developed over the years, its methods evolved to accommodate advances in the build strategy. There was no prototype to work from, no test model as a point of reference. It had to be right first time, although emergent first of class issues were inevitably encountered as the programme progressed.

Modular build proved extremely beneficial, a method that allowed large, complex modules to be outfitted and pre-tested prior to transfer to the DDH on huge, multi-wheeled transporters. It was one improvement in the construction process that helped save thousands of man-hours and, importantly, reduced many of the safety risks associated with the previous approach.

With space at an absolute premium on board Astute – its machinery and equipment is three times more densely packed than that of a surface warship – any such opportunity to complete tasks off the boat are more than welcome.