I thought I had it heard somewhere else, but that might only be a wrong déjà entendu.

'Squallor' was but my invention when I listened to the first verse. I heard 'squall*' and found the verb 'squall' in a dictionary. I thought 'squallor' might be a fine noun to that verb matching the phoneme. Last night, with a much bigger dictionary, I found 'squaller' as Malcolm has already pointed out to be correct.

Wolfgang