"Merry Xmas Song" foi registrada entre novembro e dezembro de 1969, durante as sessões de gravação da trilha sonora do filme "Zabriskie Point". Esta canção continua na lista das músicas inéditas não lançadas oficialmente pelo Pink Floyd.
A faixa conta com a participação do radialista John Peel e do roadie Alan Stiles, que é homenageado pelo Pink Floyd na música "Alan's Psychedelic Breakfast" e aparece na capa do álbum "Ummagumma".
One, two, three, four
Here comes Santa in his sleigh
Those silver bells they sound so gay
His shiny sleigh is heaped with toys
To give to all good girls and boys
With dolls and gollywogs and clockwork trains
Trams, tin soldiers and little model planes
Going to fill your stocking so long as you've been good
And I'm sure that you have because you know you should
Middle eight!
"Have I got to sing that?"
"Yes!"
"No you don't sing, you just say it."
"Okay."
"All right?"
"Right."
"One, two, three…"
Cheerful face is wreathed in smiles
Can see him coming for miles and miles
As he passes by he'll catch your ear
With "Merry Christmas guys and a Happy New Year!"
"Man!"
"Shout that as a cheery Christmas greeting, Alan."
"Yeah, shout that one out, right?"
Turkey and sausages and Christmas pud
"Have another helping John!"
Oh, I don't think I could
Christmas parcels under the tree
None for you and six for me!