James , Viscount Severn is one of the children of Prince Edward and Sophie , Countess of Wessex .
James , Viscount Severn -LRB- James Alexander Philip Theo Mountbatten-Windsor ; born 17 December 2007 -RRB- 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 .