Answer from an English teacher
The first is the unstressed version, the second the stressed (for example at the beginning of a sentence) so both are correct.
Not that deeming one pronunciation 'correct' is anyone's business anyway. There's nobody governing the English language.
( Zuowan, Sun 10 Jul 2005, 12:11, archived)

Tell that to my gran.

( Reid got it going on like Donkey Kong, Sun 10 Jul 2005, 12:15, archived)

With pleasure.
Where is the old dear?
( Zuowan, Sun 10 Jul 2005, 12:19, archived)

response from another english teacher
you might be an english teacher but you've not understood the question. In received pronunciation, the letter H is pronounced 'aitch', not 'haitch'. No argument about it. It's like saying that W can be pronounced 'double U' or 'Wubble U'.

EDIT:

I just researched this in some etymological books what i've got and apparently the origin of 'aitch' is 'ahha' or 'acha' where the central sound represents the original guttaral 'h' of the semitic language. so there is no need for an initial aspiration.
(Brad Dice, Sun 10 Jul 2005, 13:00, archived)