Volume Twelve - Pre-Victorian to the Present Day - further aspects - Trials of Welsh and Mixed Coals . . .

In a similar vein, the commander-in-chief of the Channel Squadron wrote:

the smoke produced by using the present mixture of north country and Welsh coal, combined with that from guns in action, renders seeing signals, or even ships impossible, and is a question for serious consideration.

I would recommend returning to the use of Welsh coal.

There were also complaints that ships could remain at sea for less time using a mixture of coals rather than just Welsh coal, and that additional expense was incurred as a result of the damage caused to boilers and furnaces by the fierce heat of north country coal. Moreover, in practice, it had proved impossible effectively to mix Welsh and north country coal in the stokehold.

Initially, the naval authorities were inclined to denigrate reports which commented adversely on existing fuel policy. However, as the evidence against mixed coaling arrangements accumulated, the official attitude altered, and after 1872 the Admiralty acknowledged the superiority of Welsh coal for maritime use by buying almost all its supplies from south Wales.

The Admiralty's 'seal of approval' came at an opportune time because it placed south Wales in an advantageous position to meet the huge increase in the demand for steam coal associated with technological change at sea during the late nineteenth and early twentieth centuries. . . . .