They had lost Ireland (1922), Egypt (1922), Iraq (1930), and South Africa (1932). Their dominance over China (1832) was greatly reduced after the Boxer Rebellion (1900). And South Asia was already collapsing.
The Empire was India or nothing. It wasn’t until India went in ‘47 that the decline was irreversable.
Remember, they lost the US in the 18th century and proceeded to dominate the 19th as well. The British Empire wasn’t weak. And certainly they didn’t fear the Ottomans at any point in time. The Porte hit their peak long before the Empire did.