A boat worker inadvertently hooked an unexploded ‘tank mortar’ when using a magnet to fish for scrap metal in the Grand Union Canal. The incident occurred at Kings Langley and required the attendance of an Explosive Ordnance Disposal (EOD) team, who removed the device for safe disposal.
Canals are common locations for Unexploded Ordnance (UXO) finds, with many surplus or ‘souvenir’ munitions having been disposed of in these waterways over the years.
See: http://www.watfordobserver.co.uk/news/16198833.Unexploded_bomb_found_in_canal/