Actually at some point in early 1943 the US Navy overtook the Royal Navy in number of capitol ships. Max Hastings (in Winston’s War as I recall) points to that as the end of the British Empire.
From Trafalgar to 1943, Britain ruled the waves.
An Arab couldn't believe a man would follow a Queen. He told Laurence that ‘My king has a dozen cannons, how many does your QUEEN have?’. He gave some diplomatic answer, but my answer would be....... “Half.”.
“Half of a cannon?”
“No, of all the cannons that there are in the entire World, My Queen has half of them.”
That would be a reasonable assessment at the time, of the cannons worth having at least.
Keegan and others make the point that the British empire probably died at the Somme in 1916. I’ve read other sources that indicate their intervention in Suez in 1956 might be, and there is a good argument the Falklands War might have been its last gasp. It took Rome nearly 300 years to fall after Commodus’ assassination...Perhaps there is even a case for the end coming starting with a certain failure in 1776.... Hastings’ point is equally valid- historians will be debating the point where the British empire was finished for many years yet.
When thinking about this I am reminded of an episode of Monty Python- they first flashed a screen that said “By 470 the Roman empire lay in ruins...” A few skits later another one came up. “By 1970 the British Empire lay in ruins...”
Hope this helps,
dvwjr