The vowels of RP commA

[ə] is the sound in all RP varieties, as with lettER. In the case of RP, [r] is used to create a link to a following word beginning with a vowel although, unlike with lettER, this is not supported by the orthography. This so-called <r> intrusive , although now “used freely in mainstream (native) RP” (Wells 1982: 284), is abhorred by many advocates of more restrictive varieties of the accent, and rarely features in its description in teaching texts or dictionary transcriptions.