Loss of Empire may be more relevant to other countries. The UK was an economic black water in the 1950s and remained so until the 1980s. Are we debating global political influence or economic bailouts?
For instance Spain's wealth was based on its empire. Its decline though based on the loss of global power was largely the result of poor political choices.
France made costly errors to hold onto her Empire. I would suggest that this cost resulted in the French creating the founding blocks of the modern EU. As France needed to protect its uncompetitive economy.
Britain actually has done well economically post-Empire and through the Commonwealth, P5, etc. has remained globally important. However the UK would be wealthier had the Empire remained. This is though a result of rapid economic collapse in many former colonies due to weak or corrupt leadership. Faltering economies - and sometimes anti-British governments - naturally decreases trade and wealth creation.