Commons Briefing Paper 7212, sections 5 and 6 (“This Bill … does not contain any requirement for the UK Government to implement the results of the referendum”).
Statute for EU Referendum compared with statute for AV Referendum, indicating no section on criteria for implementation (section 8 in AV Referendum)
Standard Note PC02809, describing UK system as “consultative”, p. 13
Commons blog post by clerk Elise Uberoi (author of Briefing Paper 7212), describing MPs’ need to balance constituents’ wishes with “enlightened conscience” (a reference to Edmund Burke)
MPs’ Code of Conduct; III, 6, “a special duty to their constituents” and “a general duty to act in the interests of the nation as a whole”.
You can also draw your MP’s attention to the Government’s own statement of these “interests of the nation as a whole” regarding Brexit, in leaflet of 11-13 April 2016, namely: “This leaflet sets out the facts, and explains why the government believes a vote to remain in the EU is in the best interests of the people of the UK”,
You can question your MP on the legality – or at least propriety – of the Government declaring, in its leaflet, “we will implement what you decide”, without supporting basis for this promise in statute passed by Parliament
And you can question your MP on the justice of Phillip Hammond’s exclusion of 16-17 year olds, EU-27 citizens and over-15 year ex-pats from the franchise, on 9 June 2015. Irish citizens got the franchise, and they are EU-27 – so why not other EU-26?.