Why coast batteries could mix unlike heavy guns

Why did the Dover coast guns include heavy weapons from different sources and calibres?

Land installations could use any available barrel and support unlike weapons from separate stores, a logistical luxury unavailable aboard ship.

The Dover gun programme drew weapons from available stocks rather than insisting on a single standardized type. Fixed positions have more room for magazines, workshops and separate supply chains than ships. A coast battery can therefore maintain several unlike guns from different warehouses even though the arrangement is logistically inefficient. A warship cannot spare the same volume or handling complexity, so naval batteries demand much tighter standardization.