The British in India had relatively few lines they wouldn't cross, for example famously after a "mutiny" (attempt to regain independence) they tied the "mutinee

The British in India had relatively few lines they wouldn't cross, for example famously after a "mutiny" (attempt to regain independence) they tied the "mutineers" over the mouths of cannons and fired through them. What they did have was a busted economy after WW2, no access to international credit and a treaty with the Americans that was forcing them to decolonialize. The ongoing independence campaign (mostly paused during the war) put them in the position of "double down or fold" and they chose to fold. I think people overestimate the element of ethical embarrassment.