I think it was pretty obvious by the mid-'20s that India (and other territories) would be decolonised sooner rather than later, if not the exact timescale.
I do get your general point, though - and perhaps the most interesting thing is that the foundation of the BBC comes at almost exactly the same time as the establishment of the Commonwealth.
So I think yes, it was a kind of mouthpiece for a British sense of benevolent world leadership, absolutely. But not of empire in an aggressive/expansionist sense.
Barnaby is a journalist based in Suffolk, UK. By day he covers science and public policy; by night, film and classical music. He has also been a cinema manager.