LONDON (Reuters) - A senior British government source said that the European Union had to give ground or there would be no trade deal by Dec. 31, when a Brexit transition period expires, a Times Radio reporter said. “Much might depend on whether the EU think the PM is bluffing about no deal. No10 adamant he isn’t,” Tom Newton Dunn said, referring to 10 Downing Street, Prime Minister Boris Johnson’s office. Newton Dunn added that a senior government figure had said the EU had to give ground or it would be “no deal, ‘and that’ll be that’.”