Could the British have won the Second World War on their own?

Saying this in the sense of the British Commonwealth, on their own, forced to fight Germany, Italy, and their allies on their own. This was the case for a good year, so I suppose they certainly thought they could do it, or were sure an ally would join that would turn the tide, but I'm curious about whether the British Empire could really do it on its own.

To my knowledge, the RN would certainly triumph over the Italian Navy, if it fully committed, and the Kriegsmarine wasn't much of a threat aside from the submarine threat. I'm thinking that, in this scenario, the British wouldn't receive lend lease or any sort of material aid (i.e. no more Destroyers for Bases) from the USA, so it would be purely British resources.

purely hypothetical ofc, im totally not in a position to alter history in such a way that the above takes place