The other day I was engaged in a stupid debate on the proper use of the word “an” before the words History or Historical. There seems to be no firm answer as to what is the case. While “a history” is more common and accepted, “an historical” is still widely used. So I did a bit of deductive reduction.
The use of “an” before an unvoiced consonant is traditional, but is changing as the H is more often voiced. That said if you come from an area where your accent still drops the H then an, is more correct. How odd would it be to say “a istory” does not the phrase “an istory” sound better?
In English we don’t pay a lot of attention to liaisons as is done in French but we do have a few. If you say quickly the following phrase does it sound bad? – An istory of the English Language? No it doesn’t, because there is a liason between the two words they often come out in some accents as “anistory.”
So the rule I go by is for Canadian and American usage “a History” works but “an historical” is correct. If however you have a London accent “An History” is best. In reality there is no correct usage, use what suits your audience.