No, there were engines that were capable of flight, guns capable of rapid fire, television technology and radios.

That was "advanced modern technology" then, and as the passage of time has marched forward, what we consider modern changes - so what's your point?

How many of TVs were there back then? I can tell you that very few in my country, now everybody has a smartphone.

Also I can tell you, no airplanes or TVs were built in my country either. They never were, 100 years ago, 50, 20 or nowadays.

So when you said “The idea of the majority of manufacturing being external to a country” you must have meant the US.

I meant the UK.

Domestic production of goods such as televisions, radios and even extremely high technology such as tractors has been declining since the 70's.

If you go far enough back (100y or so) then "imported" usually referred to raw materials, spices or very exotic equipment such as furniture - the supply chain and tooling was mostly domestic.