Yes, Buddy, my @22 is very British and I should have remembered our several non-UK setters.
The late Tommy Cooper was a comedian/deliberately failing magician whose trademarks were a fez and a catchphrase: 'Just like that!' to indicate the conclusion of a trick. I am suggesting that phrase to be the equivalent of another, perhaps uniquely British, phrase: 'at the drop of a hat', meaning 'immediately, on the smallest provocation'. A bit tenuous!