Europe was awash with guns after both world wars. Now it isn't. How did that happen?
Mostly down to a Parliament dominated by upper/upper-middle class MPs who were concerned that our trained population with combat experience might follow the Bolshevik example.
That was pretty much the exact reasoning for the Firearms Act 1920 - make rifles and pistols expensive, price out the plebs, reduce the risk of armed insurrection. The "licence" was much like a modern Rod Licence - pay yer money, no further checks other than being able to afford one obviously meant you were "the right sort of person".
Which at it's most reductionist comes down to... oppression of the working classes by the political elite in maintenance of the status quo.