As expected, or at least hoped for, the presence of Kris Kristofferson as an opening act on the bill did result in a Star is Born flashback, as the duo revived "Lost Inside of You," a number from the 1976 movie that some fans insist should be an evergreen, too.

Following the obligatory rendition of "Evergreen" - the other song she co-wrote for the film in question - Streisand brought to the stage "one of my favourite leading men ... Here's a song that we sang together in the movie, right? I love this song," she declared.

Although the song is unremittingly hopeful in its romanticism, there was added bittersweetness now as it began with the line, "Time has come again..." Streisand's co-writer on the tune, Leon Russell, is no longer around. Kristofferson, thankfully, still is, and although Streisand has to do even more of the heavy lifting now than she did in 1975, her duet partner looked pleased to be reigniting the chemistry that captivated moviegoers 43 years ago.

"Lost Inside of You" has remained an underdog in her catalogue for most of the intervening years, as she has seemed reluctant to revive it as anything other than a duet.

Streisand has only ever added the song to her set list on her 2012 and 2013 tours, where it was performed in partnership with her tour mate at the time, Chris Botti. But the faithful have long wanted to see her on stage again with her movie mate, with or without a bathtub anywhere in the vicinity.

Streisand was performing in front of a sell-out crowd of 65,000 at Hyde Park, said to be the biggest audience she's performed for since a Central Park gig for 150,000 in 1968. Kristofferson was actually third down on the all-day bill, separated from the headliner by a set from Bryan Ferry.

Although no one could be certain Kristofferson would be taking the stage with his former co-star after his preliminary set, he couldn't really be called a "surprise guest."

That title fell to Lionel Richie, who joined forces with Streisand in the second half of the show for "The Way We Were," a song they premiered as a duet on her 2014 "Partners" album.

The set list was considerably different than it was for the two lone shows that Streisand performed last year in New York to close out her long-running "Barbra: The Music, the Memories, the Magic" road show.

Australian Associated Press