Paul McCartney has slipped two hidden tracks onto his new Flaming Pie box set. At the end of the demo of "Heaven On A Sunday," there's a minute-and-a-half of McCartney and Ringo Starr joking around during the sessions for "Beautiful Night."

After McCartney's home demo of "Great Day," which was written back in 1969, "Macca" tagged on a 30-second snatch of him playing the tune from his August 24th, 1974 "Backyard" session at Abbey Road Studios while filming Wings' long-unreleased One Hand Clapping movie.

To this day, the track remains the only officially released song from the infamous backyard session to be officially released on CD. McCartney had previously issued his take on Buddy Holly's "Peggy Sue" on his 1986 The Paul McCartney Special, and "I'm Gonna Love You Too" and the original "Blackpool," were featured in the menu section of 2007's The McCartney Years DVD.

McCartney was asked about his memories of the Flaming Pie album on the "You Gave Me The Answer" fan-generated section of his PaulMcCarrtney.com website. He said, "I remember just having a laugh with Jeff Lynne, and the various people I worked with on the album. We had quite a lot of fun making it -- Steve Miller, Jeff Lynne and I, and Ringo (Starr) was there too. So, I think those are my favorite memories, just working with them all."

The new hidden track of Ringo and McCartney joking around during the Flaming Pie sessions spotlights one of the Beatles' greatest assets -- the brilliance of Ringo: "That was our great saving grace. Ringo, he said, 'Oh, God, it's been a hard day's night' -- and he'd mean it. He wasn't trying to be funny. He would sometimes just get words a bit mixed up. I remember Ringo once in a cafe, he said, 'Can I have slight bread, please?' (Laughs) And we'd all fall on the floor, y'know? And he'd sort of: 'What's wrong, slight bread? Y'know, I mean just a little' (laughs)."

AUDIO: PAUL MCCARTNEY ON RINGO STARR'S WORD PLAY