I Believe In Father Christmas by Greg Lake is in D at 116 beats per minute and runs 2:11 across 15 bars. It uses 6 chords — G, D, Am7, A, Dsus2, Am11. The chord diagram changes as the song plays and the words light up as they are sung, so you can strum and sing along without reading ahead.
Want the melody line note by note? I Believe In Father Christmas guitar melody tab.