So if you ever wonder why Germany and Japan became so strong economically thats why
Well, when WW2 started Germany was also very strong so the excuse of "free American money" (which wasn't really free) doesn't really cut it.
Frankly, Britain had all its chances to become as successful as Germany but pissed it away through laziness and the general incompetence of British leadership. Blue Streak isn't the only case study which demonstrates this (until this day far Britain is the only country on Earth which was on the path to obtain its own space platform, something every other country aspires to, and simply wasted it), there are many similar failures like TSR2. Ask yourself why famous British brands like Mini, Jaguar, Land Rover/Range Rover, Rolls Royce, Bentley and all the others that once had been famous for their poor workmanship and horrible reliability have flourished since they went under foreign leadership. But be careful, because you might have to face some uncomfortable facts about British culture and attitude.
There is a reason why Germany is, again, an economic powerhouse producing some of the best engineering in the world, while Britain is now busy dealing with the mess that is BREXIT. And it has nothing to do with "free American money".