Why and where is it performed

The first part of this question is difficult to answer as nobody really knows!  It is certainly a very old tradition and is said by some to pre-date Christianity and have a ritual or ceremonial significance.  As to 'where', the tradition was once widespread across Europe but in England was, and still is, mainly associated with Yorkshire.  Locally, there were teams at Loftus, Boosbeck, Lingdale, Skelton, and North Skelton.  The dances were normally performed in mid-winter with Boxing Day being the preferred day for performances when the teams would tour the local villages.