I don't agree. We don't even vote for a party - we vote for individual MPs, and the one winning the most seats is invited to form a Government. Or in 2010 and earlier cases, where there is no overall winner, the losing PM is first offered the chance of forming a Government.
Until Theresa May wins her own mandate, that of the party which formed the Government stands.
It was, as was made clear, and ADVISORY Referendum.We expect Parliament to take note of this but to do their duty and act in accordance with what they perceive is the good of the country, and then represent their constituents.
How would you be arguing now, if Remain had won, and the winner had said 'Right, that now gives me a mandate to join the Euro and become part of Schengen?