It's common in Scottish and Irish English. It is not uncommon in England among older speakers, especially those from the 'higher social classes' and/or those educated at public schools*.
I** find that I use /w/ in normal conversation, but /hw/ ([ʍ]) if I am delivering a formal presentation. This is probably a hangover from my days at school, when it was drummed into me that /hw/ was the 'correct' pronunciation.
* 'public schools' in Britain are prestigious private schools.
** I am 65, from the south of England.
Last edited by 5jj; 09-Apr-2011 at 20:47.
Reason: explanatory addition - 'in Britain'.