British use of a/an before words that begin with a consonant
Solution 1:
It's not limited to Great Britain. We do it sometimes with some words in American English, too. It is not, for example, uncommon to see "an history," particularly in academia. I remember my high school American history textbook was titled "An History of the United States," and I remember asking my teacher about the use of "an" instead of "a." She said the use of "an" instead of "a" was just with the word "history" in formal communication, but since then, I've seen and heard other examples of "an" being used in American English before not just "history" but other words with a hard H, too, but it's normally in an academic setting or in a documentary or something like that and it's with just the rare word.
I couldn't find my high school history textbook, but I did find this history book published in Philadelphia that uses "an" before "history":
Historical Collections, Vol. 1: Consisting of State Papers, and Other Authentic Documents, Intended as Materials for an History of the United States of America
Here is another example where "an" is used before "heroic" in The United States Democratic Review, Volume 15:
"Those whom we have hitherto noticed were the men of an heroic age."