The British economy grew after WWII, in the era when the Empire was dissolving, but it grew slower than other European economies (which admittedly started from a lower and more war shattered base). It also grew more slowly than the USA.

Here is GDP growth by decade for Britain vs other European countries for the decades after WWII up until 1980:

UK:______1950-60 - 2.7, 1960-73 - 2.3, 1973-79 - 1.6

US:______1950-60 - 3.3, 1960-73 - 4.2, 1973-79 - 2.7

Germany: 1950-60 - 8.0, 1960-73 - 4.4, 1973-79 - 2.4

France:___1950-60 - 4.6, 1960-73 - 5.6, 1973-79 - 3.1

Italy:_____1950-60 - 5.5, 1960-73 - 5.3, 1973-79 - 2.6

(Source: http://www.rozenbergps.com/books/britain/kern.pdf)

After 1980, Britain’s relative economic growth turned around.

From 1980 to 2008 Britain was the only major European economy to grow faster than the USA.

Here is a look at GDP per capita compared to the USA (USA = 1.000) from 1980 to 2008.

UK:______1980 - .688, 1994 - .705, 2008 - .765

Germany: 1980 - .803, 1994 - .812, 2008 - .763

France:__1980 - .780, 1994 - .730, 2008 - .713

Italy:____1980 - .756, 1994 - .754, 2008 - .675

(Source: www.themoneyillusion.com/?p=5164)

So, British GDP per capita has been improving relative to the US between 1980 and 2008. Meanwhile, the other main European Economies were slipping relative to the US. The UK economy has been doing better than the rest of Europe from 1980 to 2008. It was doing worse than the rest of Europe before 1980.

Whether the relatively poor performance of the British Economy in the first 35 years after WWII was due to adjustments to the loss of the Empire, or whether it was due to adjustments to more socialist politics, is hard to tell.

In any event, such effects seem to have dissipated around 1980, and the British economy has been performing relatively well again.