@tanukihat : I am British, and the "h" in "history" has never been silent. Not to say I haven't witnessed people using "an" before it from time to time, but that was in spite of it NOT being silent, which just made it all the more jarring.
The letter "h" in general is suppressed in a lot of accents here, but that doesn't make it silent, and it tends to be a trait of.... what were formerly lower class accents... so it used to be looked down on. These days I'm pretty sure people just don't care.
Obviously the "h" in "herb" has never been silent here either, and I've no idea why the americans decided to try and make it so... or at least in the non-name term (since apparently even they can pronounce "herb" correctly if it is part of a name).