My parents used to call each other “Blick” as an ironic term of endearment, and maintained that it was short for “blighter”. Perhaps only for them it was…
Either way, there’s a delicious self-mocking in the word. Whether an Englishman calls his homeland a “Foreign” or a “Blighted” place, there’s a built-in joke. It’s charming.
Wrong, they were building a two-storey house one time and decide to “bung a low roof on it”, hence the name.