Sightings of a black ring in the sky above Warwick last Friday have been the cause of much mystery this week.
Videos and photographs have been sent in by readers who have been baffled as to what the ring actually was.
The strongest suggestion is that the ring, which stayed in the sky for about three minutes before disappearing, was the smoke from new pyrotechnics currently being used as part of the attractions at Warwick Castle.
A castle spokesman said: “As part of our 1,100th anniversary celebrations this year, we’ve been testing a number of fire effects to enhance our daily Trebuchet Fireball Spectacular show – the world’s largest firing catapult.
“We’ve seen a number of different effects including the vortex images that have been reported.
“As yet we don’t know what causes the phenomenon but it’s certainly a spooky spectacle.”
Historic Warwick sent in a photo of the same type of black ring in the sky above Mill Street last Saturday evening and on Twitter said: “It’s the new pyrotechnics for the Warwick Castle trebuchet.”
The smoke ring explanation is also supported by a similar event which occurred in Pinellas County, Florida, in the USA last October when the same type of ring was created by a fireball of gasoline and diesel fuel fired from a huge mortar during the testing of a fireworks display.
But some have other ideas as to what the black ring was or what caused it.
Schoolgirl Georgina Heap, who was among a crowd of onlookers last Friday, shared the photos she took with national newspaper the Daily Mail and said the ring was the “weirdest” thing she had ever seen.
Also talking to the paper, UFO expert and government adviser on unexplained phenomena Nick Pope said the circle could have been either a smoke ring, some sort of meteorological phenomenon or even a giant swarm of insects but that if the latter were the case it would be a ‘real-life X-File’.
Warwickshire Fire and Rescue Service had no reports of fires at the time of the sighting.