Link: “scolding water – John Wells’s phonetic blog”
This helped to explain a phenomenon I’ve noticed, where some words (like fault, false, alter, because – although that last one isn’t really explained by this link) are pronounced with the “lot” vowel by most people, but with the “thought” vowel by a minority (I want to say mainly by old people), in Australian English. I wondered if it was a lot-cloth split thing (and it probably is in the case of because), but where the vowel precedes [l] it didn’t seem to be that, so I had to keep looking. Finally I found that this phenomenon occurs in RP too, and this blog post describes the class of words affected as “words like salt”. At last, some confirmation that what I’ve noticed is a well-known “thing”!