F or the last 20 years, Britain was unable to put a barrel on its tanks without buying from abroad. Relying on foreign allies seemed like a reasonable choice during years of relative security (for wealthy countries at least) after the end of the cold war.

But Russia’s full-scale invasion of Ukraine in 2022 has changed the calculation – and prompted a scramble to rearm among European countries, including the UK.

Evidence of that scramble was on display on Thursday in Shropshire, where the UK defence secretary, Wes Streeting , opened a factory hastily constructed by Germany’s Rheinmetall to make barrels for artillery and British tanks.

Such was the urgency that Rheinmetall’s chief executive, Armin Papperger, said the company had started investment “off the back of a handshake” before Christmas last year with Gen Sir Roly Walker, who leads the British army as chief of the general staff, without waiting for a formal contract.

Eight months later, production of the first barrels at the factory in Telford has…