By measure of Nominal GDP, it goes: USA, China, Japan, Germany- of which only USA, Japan, Germany have large GDPs relative to their population size.
Also am I wrong in thinking that, in the case of Germany, the East/West partition hindered their economic development?
If it is linked to massive industrialisation from WW2, why is the UK not similarly affected?
Its just population. The gdp per capita for all major western countries is similar. This question came up before and people tried to discuss this in the context of WW2 but the economical strenght of Japan and Germany is mostly related to them having a big population and being a "Western Country" ( meaning their History ). France, Great Britain et cetera all have comparable economies but are just a little bit smaller.
If you take France and Germany both have very comparable gdps per capita but totally different History in regards to WWII. WWII certainly had some effect on the economy but the major factors to gdp are geopgraphical and population. Obviously some countries had more luck with natural ressources and thus were able to increase their gdp per capita a bit. Norway and the US for example. Its kinda amusing to see that people see US economy as something special, in relative terms the US economy isn't superior to EU economies they just had gigantic natural ressources.
Especially Germany was always a pretty strong country when it came to economy, since its foundation in 1871 Germany was one of the biggest countries in Europe in terms of population. This and other factors enabled Germany to start wars on such scale, its population and economical size. The Wars didn't strenghten Germany its quite the opposite, Germany was stronger in relative terms before the wars.
Japans and Germanys economies are in the same line as most Western Countries they just have bigger population, as simple as that.
If it is linked to massive industrialisation from WW2, why is the UK not similarly affected?
First of all like said above the UK isn't really worse of than Germany when it comes to economy, at least not a lot. In case of Great Britain it should be mentioned that this country was "depending" on a lot of industries which were the first to be "attacked" by Asian countries. Ship yards for example. Germany had some more resistant main industries but the UK makes up for that with a huge financial sector.
Also am I wrong in thinking that, in the case of Germany, the East/West partition hindered their economic development?
All countries east to the iron curtain were seriously hindered by the economical policies of the Soviet Union this includes the GDR.