Had he positively ordered Mrs. Marsham, she would have sent for that lady, and have contented herself with enduring her presence in disdainful silence; but Mr. Palliser had not given any order. He had made a request, and a request, from its very nature, admits of no obedience. 
He had not ordered that she invite Mrs. Marsham, merely requested, and a request does not demand obedience. 