Why Royal Navy battleships carried main-gun shrapnel shells

Why did Royal Navy battleships carry shrapnel rounds for their main guns?

The shells dispersed large numbers of lead-alloy balls against aircraft and light or exposed targets, with a small dedicated allowance carried alongside other ammunition.

The Royal Navy developed dedicated main-gun shrapnel ammunition after the First World War and carried about six rounds per gun during the 1920s. The shell example contains roughly 13,700 lead-alloy balls, intended for aircraft and other light targets. The same ammunition could also have anti-personnel uses in shore bombardment. Its continued use during the Second World War remains uncertain, although the suggestion is that some rounds remained available. Shrapnel allowances are also proposed as the explanation for later totals of 106, 108, or 110 rounds per gun where the nominal allowance was one hundred.