Black square

My manager reported a recent UFO witnessed by her and her husband. The sighting took place in Crosby, Merseyside, at approximately 6.30pm when they arrived home from work in late October 2017. The sky was clear although the Sun had almost set. The UFO was matt black and they estimated it to be about the same size and shape as an A4 sheet of paper and around 30ft (9m) above the house. It was moving silently at speed in a direct straight line from south to north; roughly travelling up the Sefton coastline. One intriguing feature was that it flipped onto its back and then over again. I ran through the usual suspects: a drone? – too silent; a bird? – the wrong shape, too fast and direct, silent and flipping on its back; a Chinese lantern? – too direct a trajectory and travelling too fast (ditto weather balloon); a plane/ hang–glider? – too small. So I’m really not sure. I am aware there has been at least one reported rectangular black UFO from China this year but I think that was large and hovered. Anyone ideas?

PS: I’ve subscribed to FT for years and devour cover to cover every word every month. Dan Clay Merseyside