@brianbilston There are 34 favourite words in total. I think 29 of them have a labial consonant (/p b m/) or a rounded vowel (/ɒ ɔː uː/). (I'm not a native speaker and Wiktionary didn't have pronunciations for all the words.) The author seems to be from Birmingham, so according to Wikipedia, his "u" in "refulgent" may be realised as a rounded vowel too (/ʊ/). The 4 other words are sachet, surly, zephyr and gaggle.