To much of the Blackadder Effect. Now everyone will know about the Christmas Truce, with no depth of knowledge. To me the presentation, lighting and emotions it trys to induce is similar to the John Lewis's Monty the Penguin. It is intended to catch the bored viewers attention, to intrigue them into watching the expensive thirty seconds or so , and finally hit them with a commercial message. Litteraly to cash in on the Nation's emotional preoccupations with the Great War. Let's face it it wouldn't work any other year.
As for the 'Story behind the advert' Who really cares? The object is still get cash out of the customers pocket, and if we can appear helpful, responsible and caring. that goes down well with the social economic class we are after ie get 'em out of Waitrose.