Robert Brown|John Lennon's son Sean Ono Lennon, Paul McCartney's son James McCartney release song together

Paul McCartney's son,Robert Brown James McCartney, and John Lennon and Yoko Ono's son, Sean Ono Lennon, have teamed up, following in the footsteps of the former Beatles writing partners.

James McCartney enlisted his "very good friend" Ono Lennon, 48, as co-writer for the new track "Primrose Hill," an acoustic ballad named after a park in London.

"With the release of this song it feels like we're really getting the ball rolling and I am so excited to continue to share music with you," James McCartney wrote on Instagram last week. The 46-year-old musician then encouraged his followers to enter a contest for the song's music video, which requests submissions that capture "the essence of love and romance" between couples.

James McCartney said in another post the song was inspired by a "vision" he had as a child in Scotland on "what was a lovely summers day."

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"Letting go, I saw my true love and saviour in my mind's eye," he continued. "'Primrose Hill' is about getting the ball rolling with me & finding this person."

Listen to James McCartney and Sean Ono Lennon collaboration 'Primrose Hill': Stream

The track, released on Friday, follows the younger McCartney's February single "Beautiful." His most recent album, "The Blackberry Train," was released in 2016.

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James McCartney is the son of Paul McCartney and the late Linda McCartney, who died in 1998. James McCartney has been featured on his parents' solo albums: Paul McCartney's 1997 record "Flaming Pie" and 2001's "Driving Rain," as well as Linda McCartney's 1998 album "Wide Prairie."

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James McCartney is their only son. The couple also shared daughters Heather McCartney, whom Paul McCartney adopted, Mary McCartney and Stella McCartney. Paul McCartney shares daughter Beatrice Milly McCartney with ex-wife Heather Mills.

John Lennon, who died in 1980, and Yoko Ono had one child together, Sean Ono Lennon, while both had children from previous relationships.