An elderly couple innocently bought a shrub from a car boot sale - and ended up growing the biggest cannabis plant police had ever seen.

The pensioners, from Bedford, planted the drug in their garden, unaware that what they were growing was illegal.

Police were astonished when they spotted the enormous plant and spoke of their shock discovery on their Twitter account, saying: "Seized today. Elderly couple bought shrub at car boot sale, tended carefully - biggest cannabis plant we had seen."

A spokesman for the force told the BBC the plant would be collected and disposed of, and that no action would be taken against the couple.