British Beardmore gun factory producing Mark XII 30,5cm guns according to the Dutch magazine Marineblad dated 1910-1911 no.6

An item reported that the British Beardmore gun factory delivered 2-30,5cm guns which worked well and now were three to be delivered. It was the Mark XII L/50 gun with a weight of 68 tons, costs 144.000 Dutch guilders and within one year made.(1)

Note
1. William Beardmore and Company, Glasgow, Scotland.