In 1942, the British government had sent Sir Stafford Cripps to negotiate with the Congress. According to most sources (though this was not made public at that time), the Cripps Mission had proposed immediate transfer of ministries to Indian ministers, with the Viceroy being the head of government. It had also promised to consider grant India complete independence after the war (though this is more hotly disputed). Many British historians believe that after this offer India's independence had become inevitable and it could not be denied by any British government. How true is this, and why did then India witness so much anti-British feeling during World War II?
There was nothing "inevitable" about the Cripps Mission. But it DID represent the "handwriting on the wall."
The mission was undertaken to get Indian cooperation against the Japanese in World War II. To secure this, the British had to offer the Indians meaningful concessions. The rationale was the same as the the British and Americans offering China a termination of their "extraterritorial" rights in that country in 1943.
Very little came of the Cripps mission itself. But it did signal that the British Empire was "at the end of its rope." The construct I would use is "common causes," e.g. World War II (for the Cripps mission and Indian Independence), as oppose to "cause and effect" (the Cripps mission caused Indian independence).
Cripp's mission really did not make any difference in the outcome of Indian Indepence of 1947 , the reason is largely due to economy of great Britain.
Hitler destroyed the economies of Britain and France to such an extent that they were no longer able to financially maintain their military forces, and were hence incapable of containing the burgeoning freedom movements in their colonies.
Britain would have left India in 1947 purely for financial reasons, due to its wholly collapsed economy. After WWII, Britain left not only India but nearly all its other holdings, including Jordan in 1946, Palestine in 1947, Sri Lanka in 1948, Myanmar in 1948, and Egypt in 1952. For the same reason, France also had to grant independence to Laos in 1949 and Cambodia in 1953, and had to leave Vietnam in 1954.