Waar komt het Engelse gezegden "You could hardly swing a cat" vandaan, en wat bedoelen ze hier mee? Waarom een "cat"?

Het is inderdaad een aanduiding van hoe krap iets is.

Origin
Whether the 'cat' was a real moggy or the flail-like whip used to punish sailors in the British Navy isn't clear. Many reports claim that the cat in question is the 'cat o'nine tails'. As so often though, they don't supply evidence, just certainty. As a candidate for folk etymology goes the 'cat o' nine tails' story has it all - plausibility, a strong storyline and a nautical origin. That's enough to convince many people - the actual evidence shows the theory to be highly dubious. The phrase itself dates from at least the 17th century. Richard Kephale's