To the casual observer, the black flag with unfamiliar white symbols looked out of place among the colourful outfits and banners at London's gay pride march.
Maybe the Islamic State of Iraq and the Levant really had infiltrated what jihadists see as a symbol of Western sexual deviance and decadence.
CNN certainly thought so, running photographs of the flag above a banner headline, saying: "Isis flag spotted at gay pride event."
The segment was billed as an exclusive and the network even lined up one of its top security analysts, Peter Bergen, to discuss its appearance.