President of the Heritage Foundation Kevin Roberts has issued a fresh warning over Prince Harry’s US visa claims, as the royal’s residency in America becomes increasingly under threat. It comes as the conservative think tank have called for the Duke of Sussex’s US visa application to be made public, amid claims that the royal may have “lied” about his drug taking on his documents. The action by the Heritage Foundation follows the release of Prince Harry’s memoir, Spare, which included claims by the Duke of his previous drug use. Prince Harry admitted to formerly taking marijuana, cocaine and p…