James, Viscount Severn is the only son of Prince Edward and Sophie, Countess of Wessex.
James , Viscount Severn ( James Alexander Philip Theo Mountbatten-Windsor ; born 17 December 2007 ) is the younger child and only son of Prince Edward , Earl of Wessex , and Sophie , Countess of Wessex , and the youngest grandchild of Queen Elizabeth II and Prince Philip , Duke of Edinburgh .