Imagine if the referendum had gone the other way and people had voted to stay in the EU. Imagine further that the Government had said "right now we've a mandate to join the euro and the Schengen agreement". All hell would have broken loose, because of course that was not the question on the ballot paper.
And yet the mirror image of this is exactly what is in play now. The hard Brexiters are proposing that we jump out of the Single Market and the Customs Union into our own free trade agreements,; that we leave the social chapter; that we end our membership of Europol and use of the EU arrest warrant; leave Horizon 2020 and negotiate bilateral R+D agreements for the universities and abandon the environmental protections developed with our EU partners.
This cuts right across the endorsement of the Single Market in the 2015 Tory manifesto. Theresa May's foolish refusal to be open about her negotiating objectives or even to share any factual analysis - "no running commentary" - leaves the very worrying prospect that decisions will be taken on the basis of ideology and rhetoric, not a hard-headed assessment of British interests.
Already ministers are making absurd claims - Liam Fox says we live in a "post-geography trading world"; Boris says he wants barrier-free trade in the EU and to leave the Customs Union. This drew the deserved rejoinder from the Dutch foreign minister that it was intellectually impossible and politically unavailable. Yet the Dutch are among our closest EU partners, sharing the UK's liberal economic outlook. If even they are alienated we should be worried.
This is why I hope the Supreme Court upholds the High Court judgement requiring Parliament to approve the triggering of Article 50. The Government will then need to bring legislation to Parliament and at this point Parliament should assert itself on behalf of the British people on the kind of Brexit the Government should aim for. The fact is people voted for Brexit, not how to Brexit, and as of today polling suggests only a third of people would wish to leave on any terms, 48% voted remain. We need to build a consensus on the new deal.
Amending the legislation to incorporate negotiating aims is not the same as vetoing Article 50. While I sympathise with colleagues who wish to do this because their constituents voted remain (the legislation for the referendum was only advisory), my constituents voted to leave and I believe it's more important to get the right Brexit.
It is reasonable to interpret the referendum vote as a desire to see immigration from the EU controlled and the end to jurisdiction by the European Court of Justice. This being the case, continued membership, but not access to, the Single Market is ruled out. That does not however mean we need to leap to the wilder shores of Liam Fox's fantasies.
My starters for six would be:
• Maintaining all social chapter rights.
• Staying in the Customs Union (the original Common Market, which is very popular).
• Continuing to participate in the Horizon 2020 research programmes and its successors.
• Maintaining policing and security co-operation through Europol and the EU arrest warrant.
• A soft border between Northern Ireland and the Republic.
• The maintenance of "pillar 2" payments for farmers to protect the environment and the ETS carbon trading scheme.
Stephen Kinnock has argued that the Article 50 leaving process is separate from the Article 218 new relationship process. This is legally true, but in practice the terms on which we leave can constrain the new relationship as is evident with say the Customs Union or the Northern Ireland border. So in practice the two negotiations will be interlinked.
It then follows logically that at the end of the negotiations Parliament and the public be consulted on the terms. The linkage between negotiating aims and approval should be retained to demonstrate good faith and build trust. No-one is being over-ridden. The purpose of a further democratic exercise at that point is not to subvert the will of the people it is to make sure that command of the nation's direction is not in the hands of a tiny group of ideologues who want to turn us into a low wage, offshore tax haven somewhat akin to Belize.
I don't believe that a series of select committee inquiries or debates without votes can deliver the leverage needed to control this Government, as their continued resistance to the court case and criticism of the judges indicates.
I believe we become a credible opposition when we stand up for the interests of our constituents and don't allow Brexit to become an opportunity to scrap so many valuable achievements this country has secured over the past 40 years.