The Allerton Oak grows in Liverpool’s Calderstones Park. According to legend, judges in medieval times would meet under the branches of the tree, as they lacked a courthouse. Legend also states that the crack in the tree appeared in 1864 when a ship carrying gunpowder on the Mersey exploded. It was heard 30 miles away, and smashed thousands of windows. In World War two, Christmas cards containing leaves from the oak were sent to Liverpool parks staff who were fighting abroad – a reminder of home.