Robbie the Reindeer: CGI or stop-motion?

Having viewed the newest Robbie the Reindeer special from Aardman Animations ("Close Encounters of the Herd Kind", I was a little bothered by one aspect. Does anyone (well, any British viewers, as it hasn't and probably won't appear on American television) know if it was made with stop-motion animation that Aardman usually works with or if it was done with CGI (like Flushed Away)?