BRUSSELS (Reuters) - It is up to Britain, rather than the European Union, to make progress in divorce negotiations with the European Union to enable the opening of talks on the future relationship, the spokesman for the European Commission said on Monday.  There is a clear sequencing to these talks and there has been so far no solution found on step one, which is the divorce proceedings,  spokesman Margaritis Schinas told a regular briefing.  So the ball is entirely in the UK court for the rest to happen. And the UK can always refer to the debate in the European plenary in Strasbourg on the subject,  he said, referring to last week s debate in the European Parliament. He was responding to excerpts made available of a speech  British Prime Minister Theresa May to Britain s parliament later on Monday in which she will say that  as we look forward to the next stage, the ball is in their (EU) court . 