I'm not sure what the confusion is. It is the lack of stress on the opening syllable rather than any French provenance - as some claim - that matters. Hackney, hearse, homage and hostage, for example, all came to us via French, too, but I do not know of any evidence that British people - other than Cockneys etc - ever said 'ackney, 'earse, 'omage or 'ostage. It is probably because of such words that the relevance of French pronunciation has been doubted as regards the 'an (h)otel' usage.
Much more significant surely is the fact that all four of these words open with a stressed syllable which 'hotel' etc do not. It seems most probable, therefore, that stress-pattern is far more important than French origin in this matter. The final nail in the coffin of �The French Connection' is the fact that Fowler's Modern English Usage does not even mention a French factor here. On the other hand, it does indicate the relevance of the unstressed opening.