Hollywood superstar Leonardo DiCaprio reportedly walked friend Kate Winslet down the aisle when she married for the third time.

Winslet, 37, married 34-year-old Ned RocknRoll - whose uncle is Virgin tycoon Richard Branson - in what a source described as "a really romantic, private ceremony".

The wedding was kept a secret, and even the couple's fathers were surprised when they heard the news after being contacted by reporters.

"The wedding took place in a converted barn and was attended by just six friends from each side," The Daily Mail reports.

"Kate's children Mia and Joe, from her previous marriages to film directors Jim Threapleton and Sam Mendes, were also there."

RocknRoll, who changed his name from Abel Smith, is the son of Branson's sister.

"Ned . . . has also been married before. He split from aristocrat Viscount Cowdray's daughter Eliza Pearson just 20 months after they married in 2009," according to The Mail.