A US-style yellow school bus with a banner depicting the face of Prince Andrew has driven past Buckingham Palace, urging him to testify in the investigation of the late sex offender Jeffrey Epstein.
The stunt organised by US lawyer Gloria Allred sought to pressure the Queen's son to reveal what he might know about the disgraced US financier.
Allred represents some of Epstein's victims and has demanded that Andrew co-operates.
Andrew has stepped back from royal duties following a catastrophic BBC interview in which he categorically denied having sex with a teenager who says she was trafficked by Epstein.
US attorney Geoffrey Berman told reporters in January that Andrew has provided "zero co-operation" to the FBI and US prosecutors seeking to speak with him about Epstein.
The statement by Berman, the top federal prosecutor in Manhattan, was the first official confirmation that the leading US law enforcement agency had sought - and failed - to obtain evidence from Andrew, third child of the monarch, despite his pledge to co-operate with legitimate law enforcement agencies.
Andrew was reported to be "angry and bewildered" at the comments by US authorities, with the Telegraph quoting a source as saying: "The duke is more than happy to talk to the FBI but he hasn't been approached by them yet."
The US prosecutors have since stood by their statements.
Australian Associated Press