OK thanks for taking the time to formulate a comprehensive reply.
I agree that the starting point should be the referendum result – which was to leave the EU.
I would separate your line of argument into three main positions, the first that:
“The Government, with a completely different cabinet and leader, were elected on a manifesto of remain.”
True – however they were also elected with a manifesto to stage a referendum and there is no compunction to hold another election even if they failed to meet a contradictory manifesto promise – especially under the Fixed Term Parliament Act. If they WERE to stage a General Election tomorrow I think we all agree that Theresa May would be returned with a larger majority than she has now and would therefore be given a mandate for a Hard Brexit so – while you may rightly feel this way – I would say that this point holds relatively little water. Secondly:
“David Cameron fucked up the referendum question”
“.. the destinations that are possible having started on this route are so varied [..the decisions of EEA membership and the like are so important ..] that the people should be consulted.”
This is more persuasive however it has to be categorised as a political rather than a legal question. I agree with you that the referendum question was “fucked up” – simply put, David Cameron did not do his homework and I’m astonished that he did not specify a supermajority qualifying vote. But nevertheless, having taken the vote we are now where we are – which is to trust Parliamentary democracy to be accountable to the people ( I understand that you feel this is inadequate as it will “be too late” the next time politicians are held to account).
The problem with being a political issue is that it needs a political solution – and right now I do not feel that there is sufficient appetite or political will in the country to follow this course. If there is then Owen Smith, the Lib Dems and the like will profit from it however that would invalidate the original referendum since it was made clear before the vote that NO second referendum would take place otherwise the margin of “Leave” would have been likely to have been much greater as the electorate would regard it as a less-risky option to take. In addition, there would be no incentive for the EU to offer us a good deal in negotiations knowing that, by offering a crap deal, or even nothing at all, we would then vote to stay in the EU in a second referendum.
So while it may feel that that would be the right or the best course of action the political reality is that nobody expected a second referendum to take place on hard brexit, soft brexit, hard remain, soft remain or anything else at the time they were voting and they voted to leave the EU (and put those decisions in the hands of the politicians) regardless.
Might this situation change in the future as the public realise they are unhappy with the deal? Possibly, but right now that does not appear to be the case (as seen in the Tory opinion polls). Finally:
For major constitutional changes, a mandate is required.
..If you want to restore sovereignty to the British people, why not trust them?
There was no referendum mandate with the constitutional changes made with the Maastricht and Lisbon treaties (for example) as a parliamentary mandate was implied. The same applies here as Parliament is sovereign (with all its strengths and weaknesses including being “too late” with its accountability).
Therefore I think that the gist of your argument centres not around what is legal but what you regard as just and politically expedient. And that can only be decided by political judgement, in which, of course, you would differ from a Tory Prime Minister.
Currently, Theresa May would (presumably) say that there is a mandate for her actions given the opinion poll ratings and the fact that the British people decided to leave the EU knowing full well there would be no second referendum, that all the official channels said we would leave the Single Market and that that the main driving factor motivating them (immigration controls) are incompatible with membership of (but not access to) the market.
If you are correct then either she will be punished badly at the polls or there will be a uprising against Parliament – currently however there is little sign of either.
So, although you have put forward your strongly-held conviction, this does not “debunk” my original claim that a mandate exists for the present course of action and that a second referendum is not necessary for the PM in legal, political or moral terms.