But that requires Britain to be preparing for a major land war in the short term!
Weapons and ordnance are specialist work. The idea of Britain being able to fully fulfil the demands of an industrial war in 1914 - when the largest British army ever deployed to the field at one time before then was quite possibly at Waterloo a century earlier, when the British Army is deliberately smaller than that of almost any other power, and when the demands of the front line exceeded the ability of nations like Germany (who you laud as being "good" compared to the British "bad") to come to terms with - is silly. It would require prescience.
As it was everyone retained roughly the same shell reserve per gun pre-war (more would lead to the danger of obsolescence).
The French suffered a shell crisis within six weeks of the opening of the war. The British and Germans both lasted until November.
The French and Germans had their own shell quality problems too, it wasn't just the British - British shells failed to detonate, German and French shells had a tendency to go off in the barrel.
The scale of the artillery warfare on the Western Front was far beyond that which anyone had expected, so the shell crisis is probably impossible to prevent - it could be alleviated, somewhat, but to have industry capable of the specialized job of shell production with a maximum capacity anything like that needed in WW1 is to have industry which is far overengineered to what you need in peacetime.
Practice by batteries in 1913 used around 600 shells per battery per year for regulars and about 200 per year for territorials or reserve
http://hansard.millbanksystems.com/lords/1913/jul/02/the-army#S5LV0014P0_19130702_HOL_86
Meaning less than 100 shells per gun per year. (Battery = 6 guns)
OTL the retained reserves were something like fifteen years of peacetime training; to have sufficient capacity to straightaway produce shells at the rate required by the First World War would be fantastically over-engineered for peacetime and would require well over 95% of the capacity to go unused in a given year - and you'd have to replace it all in 1900, and again in 1906, or whenever new artillery pieces are adopted.
Given that British policy was to prepare for a naval war, and given that the Germans who prepared for a land war were caught out so by the demands of WW1, I think it is infeasible for the British to have such a large shell manufacturing industry. Nobody on Earth could buy enough in peacetime to make it remotely profitable.
ED: rifles are similar. The British in 1914 had actually just decided to switch service rifles, but the war intervened and they just made scads more Lee-Enfields instead. The reason they couldn't supply their needs was because of the first mass army mobilization in British history - everyone who was expected to fight
had a rifle, with plenty of spares, it's just that "expected" was roughly a million and instead over ten
times that number went to war.
Nobody can conjure up nine million rifles in a year unless they already have a reason to produce hundreds of thousands of rifles a year in peacetime. To give you some idea of how fast the US did it, say, they peaked at 100,000 a year of Krag rifles in 1899 - after a fairly hefty war by their standards. The British have a larger army, but not that much larger that they need to be able to produce a million rifles a month.