Fans who came out to see Paul Rodgers on his 'Free Spirit' tour in Oxford, England last night (May 14) were treated to quite the surprise with more rock royalty hitting the stage. Two of the world's biggest stars, AC/DC legend Brian Johnson and Led Zeppelin's Robert Plant, joined Rodgers to perform a cover of Barrett Strong's "Money (That's What I Want)" at the New Theatre Oxford.

It was especially shocking to see Johnson back onstage after he was forced to abandon AC/DC's Rock or Bust tour, facing permanent hearing loss if he continued to perform. The fan-shot video above captured most of the cover, starting just before Johnson's time-honored gritty wail took over for a few lines, later on trading off with Plant and Rodgers during the chorus.

Since leaving the post he manned in AC/DC since 1980, Johnson has remained busy. The singer made a studio appearance with the Greg Billings Bands on the song "Old Friends Don't Come Easy" and has been active in non-musical roles as well. Johnson landed a hosting role of a five-part radio series titled The Producers and headed up his own television series, Brian Johnson's Life on the Road.

Johnson was slated to interview a host of rock legends for the television program, including Robert Plant. The two were recently photographed filming an episode for the series (reported by LedZepNews) which could help explain why these iconic frontmen were on hand to make a guest appearance with Rodgers.

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