It was noticeable at the New Years Eve programme on BBC (separate thread) that the performers were keen to keep to the Burns original 'for auld lang syne'. However the folk process seems to be working against this with the common version of 'for the sake of auld lang syne' in more common, if incorrect, useage.

I was wondering if anyone can trace when this departure happened and how it came to be so widespread.

Also do others think this is just a (relatively small) bit of folk process not to be sneered at any more than the changes we reguarly see to documented broadside ballads, for example.