"Must Be Santa" is a Christmas song written by Hal Moore and Bill Fredericks and first released in November 1960 by Mitch Miller. A cover version by Tommy Steele reached Number 40 on the UK Singles Chart in the same year. Based on a German drinking song, (the Schnitzelbank song) "Must Be Santa" is structured as a call and response. The Mitch Miller version topped the Christmas charts in 1961. And of course there's the Bob Dylan version!
A video for this song: