Two magnet fishers have pulled out a cannon from a river in what is believed to be the first discovery of its kind in the UK.<br /><br />Dave Sonik Jordan, 46, and Raymond Harper, 73, latched onto the artillery piece while magnet fishing - which is where people use magnets to pull treasure out of water.<br /><br />It took the pair, who have been fishing together for ten years, over an hour to get the 3ft (91cm) object out of the River Don in Sheffield, South Yorks,
