At the BAE Systems combat jet production complex at Samlesbury, Lancashire, engineers busy themselves beneath a banner in the main workshed. “F-35 Joint Strike Fighter” it reads, “where our future comes together.”

Europe’s biggest defence contractor has invested about £80m in the site, building offices and production sheds for the F-35, the next-generation fighter that it is making with Lockheed Martin and Northrop Grumman, the US defence groups.