So you are recounting events from nearly 80 years ago. In the face of the Hitler’s war machine pretty much the whole of Europe rolled over very quickly. Even the British Expeditionary Force was not able to stop them and we had to retreat at Dunkirk - so we pretty much rolled over as well.
The only reason the UK didn’t become part of the 3rd Reich was the English Channel, the RAF and poor decisions made by Hitler’s High Command.
Eventually Hitler’s War Machine ran out of energy and men after intense bombardment by the US, Canadian, Australian, French, Polish, Czech, Russian, African West Indian, Indian as well as British Forces both from the air and from the ground.
The UK was a fundamental part of rebuilding Europe.
And the French suffered hugely to the Germans. The did not sit back and drink coffee. If you showed any resistance to the Germans you ended up getting arrested. If you were lucky you got put up against a wall and shot. If not you were sent to internment and concentration camps. The Poles suffered even worse.
As for you Mates company - he may well be one of the best welder’s in the UK. He probably was one of the best across Europe. The fact he is invoicing for the time he is buggered about simply means that he will be costing more than European rival companies, this is unsustainable and he will be priced out of the market.
Or he has set up a European subsidiary employing European’s to do all the work in Europe - all of which has minimal value to UK Plc.