The red coat is 'new'. Images of Father Christmas prior to about 1880 most pictures showed him with a green coat. The red became the most popular colour after the US introduction by Coca Cola during the 1930s.
In England, Father Christmas was portrayed as a green fur lined coat.
n 1931, the Coca-Cola company hired an artist named Haddon Sundblom to create the artwork for a massive Christmas advertising campaign they were preparing. Until then, the soda was primarily a summer drink, with sales dropping off sharply in the cooler winter months. Coke hoped to reverse this trend by somehow linking the drink to the winter holy, sorry, holidays ... and they decided the most effective way to do that would be to make Santa a Coke drinker. Sundblom was told to create a painting of Mr. Claus that the company could use in magazine advertisements. Sundblom's first brainstorm was to dump Nast's black and white Santa suit and adopt the increasingly more popular image of the old gent in red and white, which just happened to 'suit' the Coca-Cola livery.