Footage that shows the size of the £3.5m cannabis factory discovered in a former New Basford factory has been released by the police.The Palmerston House building on Mount Street had been blocked by a crime gang and Vietnamese men were tending the crops in the historic mill – although they escaped across nearby roofs before the police arrived.Officers broke in to the building to find 4,049 cannabis plants and they have now released drone and body cam footage of their find.The torch-lit video shows the outside of the four-storey building and then the rooms where rows on rows of cannabis plants were being grown, which they have now described as the "largest" ever found in the city.