Philip Newton's journal

and the pronunciation of -ou- in house and about, which sounds distinctively different to what I’m used to but which I’m not sure how to notate. (The first half of the diphthong sounds closer to schwa, though.)

That sounds like the general Canadian phenomenon called Canadian Raising. Basically the diphthongs /aɪ/ and /aʊ/ have their first half raised to something near schwa when they're before voiceless consonants - I usually notate them as [ʌɪ] and [ʌʊ]. This actually occurs in quite a few dialects, not just Canadian, with /aɪ/, but it's more restricted with /aʊ/.

(For some Canadian speakers, including myself, I suspect the raised and unraised versions are somehow getting delinked from their strict phonological contexts and turning into phonemes in their own right. I have a raised [ʌɪ] in 'fire', even though it's before a voiced consonant and so shouldn't be raised; thus, for me, 'fire' and 'wire' don't rhyme.)