Japanese knotweed (Reynoutria japonica, formerly known as Fallopia japonica) – ‘which can grow 10cm in a day’ – has its highest known number of infestations, 2,135,  in Whitehall, Lancashire, with Bristol being second with 1,323 infestations, and Bolton third.  Nathan Hannaway a (presumably Whitehall) homebuyer reported that it will cost him £15,000 to remove Japanese knotweed from his property [Metro, 3 August 2026].