I know the economic downturn of the World War and the victory of the Labour Party played some role in Britain deciding to quit India. Did GB have any serious economic implications because of this? There were a lot of Britons employed in various sectors in India. Did the quitting cause large-scale unemployment and downturn of British economy? How was the common public's reaction to this?
To begin, the following passage from Britain, the Commonwealth and the End of Empire by Dr John Darwin discusses the "staggering blow" Great Britain felt after granting independence to India.
That being said, after reviewing the unemployment rates for Great Britain (The United Kingdom) in the years following the independence of India (beginning in 1947), it does not appear that the rates changed as compared to the early 1940's.
NOTE: The next 3 links will connect you to a PDF. You will need to scroll or search for the specific page number for sourced information.
In fact the unemployment rate dropped from 2.5 (1946) to 2.0 in 1947.
As noted on page 462 the wartime employment rates neared 100%. Not noted but possibly assumed, post wartime employment rates remain high due to loss of life during wartime as well as job availability in disaster recovery (which certainly was evident in post war Britain after WWII.)
It seems that the public reaction to the Labour Party's direction to providing a welfare state was not met with huge opposition. In fact the voters wanted an end to wartime austerity
The Labour Party, after winning the 1945 elections began the process of dismantling the British Empire when it granted independence to India and Pakistan in 1947, followed by Burma (Myanmar) and Ceylon (Sri Lanka) the following year.
These movements along with others parallel the Fabian Movement. The Fabian Society laid many of the foundations of the Labour Party and subsequently affected the policies of states emerging from the decolonisation of the British Empire, especially India.
In conclusion, I would say that as a whole Great Britain did partially suffer in terms of world power, by granting independence to India . However, without the internal stability needed to enforce colonial or Imperial rule over India, (as well as other countries/states) India would not have provided the benefits Great Britain had once received. In regards to the return of British natives from India, I see no evidence to suggest that unemployment rates during this timespan rose. Also, as previously noted the ideas of the Fabian movement, which were pursued by the newly elected Labour party, do not seem to have been met with enough opposition to suggest there was a negative public reaction to the dismantling of the British Empire or those returning from said Empire.
I based financial growth or financial diminishment on the unemployment rates throughout the years prior to and after India's independence. The data shows that throughout these years there was no difference in the employment rate. This suggests that the financial burden of the Britons returning home after India's independence did not have a negative impact on Great Britain.
... At Independence of India in 1947 a lot of British civilians in India migrated to Australia, Canada, Kenya, Tanganyika and British outposts like Kuwait, Bahrain etc in the Persian Gulf. To start with 'white Britons' ruling India were always demographically insignificant.