ALEX BRUMMER: Warm winter weather leaves Marks & Spencer with piles of unsold woollies
![ALEX BRUMMER: Warm winter weather leaves Marks & Spencer with piles of unsold woollies](http://i.dailymail.co.uk/i/pix/2015/12/30/18/1498C0DF000005DC-0-image-m-2_1451499573949.jpg)
Interpreting holiday sales clearly has become more tricky as a result of the unhelpful addition of Black Friday which provided many consumers with Boxing Day prices in November.