Why did Great Britain develop more slowly than West Germany and France?

Great Britain, indeed, developed more slowly than the FRG and France due to the fact that instead of establishing relations with other countries, i.e. to engage in foreign policy, the country was torn apart by internal contradictions. There were two forces fighting: traditional conservatism (the Conservative Party) and the growing power of organized labor (Labor Party – trade unions). The rivalry between the two parties made it difficult to focus on foreign policy.
Great Britain became a member of the EEC only in 1973. Although, we must pay tribute, in the country during this time were carried out internal reforms, such as: 1) The system of free medical care; 2) Nationalization of a number of industries (metallurgy, domestic industry, transport, energy); 3) Gasification of London.