Key Points

In a blog post shared to his website, McCartney, 82, opened up about working with Streisand, 83, on the track, which will appear on her upcoming record The Secret of Life: Partners, Volume Two, out June 27, reported People.

"I did the session with her in LA and I was pretty terrified. I think the session was about three hours, you know, a normal kind of session, and it was produced by my friend Peter Asher," McCartney wrote. "But it started off with a big 40-piece orchestra on the Sony lot... and we were on 'The Barbra Streisand Scoring Stage,' so no pressure there!"

TThe song McCartney and Streisand sang together, "My Valentine," was written for the former Beatle's wife, Nancy Shevell, whom he married in 2011, reported People.

"I thought, 'Well, this will be easy because it's my song, it's 'My Valentine.' What can go wrong?' But what I'd forgotten was that they'd arranged it so that it had to go in Barbra's key and then in my key," he explained. "So, to get from Barbra's key into mine was kind of difficult, and I had to launch in not knowing what key I was in. Mine was lower, hers was higher. It wasn't easy at all!"

McCartney however, expressed pleasure at the idea of the song becoming something of a modern standard, as it's also been recorded by Michael Buble.

"That was another reason I did it; I thought if Barbra is going to do my song, I've got to encourage that," he wrote. "And she was great. I didn't realize how rounded she is, creatively."

McCartney shared that the recording session was filmed, and at first, he was alarmed by all of the cameras and lights. Before long, however, he remembered that Streisand is an accomplished director.

"I thought, 'Wow, you're directing it!' But then I suddenly remembered she's directed three big movies. She's a smart cookie," he wrote.

At the time of the song's release on May 16, Streisand praised McCartney in an Instagram post that featured a photo of the two of them recording together.

"What a joy it was to record 'My Valentine' with @paulmccartney. To share time with him in the studio was truly special!" she wrote, reported People.

- ANI