An elderly couple have unwittingly grown the biggest cannabis plant police say they have ever seen.

The pensioners, from Bedford in England, innocently bought a shrub from a car boot sale and planted it in their garden, unaware that what they were growing was illegal.

Police were astonished when they spotted the enormous plant.

Speaking of the discovery on Twitter, they said: "Seized today. Elderly couple bought shrub at car boot sale, tended carefully - biggest cannabis plant we had seen."

It is believed that police will dispose of the plant and no action will be taken against the couple.