not sure where it comes from - but pound to a penny, it will be the creation of some poncey Southerner who coined the phrase and who has undoubtedly never ventured North of Watford Gap.
Don't know but... I think everyone should click "thumbs down" to the second dictionary entry here. Obviously written by some insular southerner who's happy with living in a place like Stevenage. http://www.urbandictionary.com/define.php?term=grim up north
RE: Don't know but... http://www.urbandictionary.com/define.php?term=barnsley we also need to vote these down as well