I have just spent 90 minutes with my eldest offsprint discussing the history of Algeria since 1830 to present day and to some extent how that affects France's current attitudes. The EU free movement of people arises much from theories of economics than individual rights and, founding principle or not, I would not assume "clarifications" could not be agreed. It is also evident that the overwhelming vote in favour of the Greek government stood for nothing when dealing with the Greek financial crisis. So I see no obvious reason why an overwhelming win for the Conservatives helps in the EU negotiations, though it makes life much easier for the government to get its domestic agenda through. (I was interested in Teribus' three advantages for May in winning big, and two were about silencing opponents, with his first point within her own party.) But what does seem obvious is that opening a discussion by declaring those who you are negotiating with are untrustworthy is not likely to be in your own best interests.