This paper generally lends support to the arguments advanced by Awonusi (1989, 1990, 2004) and others in favour of an endornormative as opposed to an exonormative standard for English pronunciation in Nigeria. They include the fact that the existing, exonormative standard, British Received Pronunciation (RP), has undergone and is still undergoing changes in its homeland, and is not homogeneous. The heightened social mobility of today's world perhaps works against the demarcation and homogenization of language varieties, and this is all the more true of the varieties or lects that have been proposed for Nigerian English when these are related, more or less explicitly, to educational attainment. Major attention is given in the paper to a schema of basilect, mesolect, and acrolect presented by Ugorji (2010), with a focus on his account of vowels and his presentation of a mechanism derived from optimality theory for evaluating vowels in contention. The basilect and the mesolect are found to be so close to each other that they might be combined. There would then be just two varieties. In contrast, the acrolect is close to British RP, albeit with many variants due to the conflict of two standardising forces, i.e. British RP and the basilect-mesolect. The vowel system of an officially adopted endonormative standard - 'Nigerian RP' - would mainly be the same as that of British RP, but the optimality mechanism could be employed to give preference to some of the Nigerian variants for inclusion in it.