Our inability to follow through in recent decades can be depressing.
Hopefully SABRE/Skylon doesn't turn out to just be vaporware.
Having said that, London had food rationing for 9 years after the war, and really didn't have the money or facilities that the Americans had. (A B-29 was used as the mothership for the X-1!)
The W article below mentions "After the rocket plane experienced compressibility problems during 1947, it was modified with a variable-incidence tailplane following technology transfer with the United Kingdom."
https://en.wikipedia.org/wiki/Bell_X-1
Additionally, around half the X-plane pilots died, so Britain avoided a lot of test pilot fatalities. The US poured unlimited funding and talent into the program, with everybody being stars/aces (Yeager, Hoover, etc.) Both were injured seriously and almost died in various X-plane tests.
One X-plane test pilot set a record, then just quit and started a gun range.
The same happens in many cases. What's a successful breakthrough is usually not only technological. UK was extremely indebted after the second world war, mostly to USA. https://www.exchangerates.org.uk/articles/1325/the-200-year-...
Of course there was the wider sad story of management problems in UK industry and the long decline after the war.