Police stunned by elderly couple's huge cannabis plant

London (CNN) -- British police have decided not to press any charges against the elderly couple who had been unknowingly cultivating a huge cannabis plant in their garden. The plant was seized Monday in Bedfordshire, central England. The police later posted a picture on Twitter with  comments: "Elderly couple bought shrub at car boot sale," adding that it was the "biggest cannabis plant we had seen!!" The police picture posted on Twitter shows a fully grown shrub with thick foliage in the front garden. A police spokeswoman told CNN: "The plant was mistakenly bought by the elderly couple. We will not be pressing any charges. We have seized it and will dispose it." She also said that unlike what has been reported in some newspapers there was no "raid."' "The property was not raided," she said. Cannabis is classified as a Class B drug in Britain under the Misuse of Drugs Act. The maximum penalty for supplying or producing cannabis is 14 years imprisonment and/or unlimited fine.