@ David:
In all main varieties of English, the use of an as the article preceding historic (an historic) is an unnecessary affectation. The rule for the indefinite article is that we use a before words beginning with a consonant sound, and an before words beginning with a vowel sound. The h at the beginning of historic is a consonant sound, soft though it may be. As far as we know, there are no modern English dialects in which the h in historic is silent (please correct us if we’re wrong), so there’s no reason for anyone to use an instead of a before the word.
The same applies with the words historical, historian, and so on. They start with consonant sound, so their article is a.
https://grammarist.com/usage/an-historic/
peer agreement (net): +2
peer agreement (net): +3
