brussels interim brexit deal strike theresa may european commission legally bind british prime minister commit government honor gentlemen agreement eu spokesman say monday formally speak joint report legally bind european commission chief spokesman margaritis schinas tell reporters ask suggestions may minister term friday accord could change see joint report michel barnier david davis deal gentlemen clear understand fully back endorse uk government add refer side negotiator refer eu chief executive jean-claude juncker say president juncker meet prime minister may last friday morning ascertain precisely case shake hand may shake gentlemen 's agreement brexit deal eu say