This may be a genuine unknown, and if so, it is an excellent UFO photo, reminiscent of the images taken by Ed Walters in Gulf Breeze Florida in the 1990s. There is a possibility also that it is some sort of hot-air balloon, which is suggested by the flickering flame in the base, and its slow trajectory of descent.

Story Source:
http://www.cornwallcommunitynews.co.uk/2013/04/05/ufo-must-be-joking/