Well, John, that rather sums up the numbskull proclivities of the supporters of the 'Brexit' fiasco. Sub-'Gove', if such a being is possible.
Professor Dougan may have established himself as a leading authority on his subject, weighed internationally against rigorous academic standards of enquiry and discourse - but the 'Brexit' supporter's answer is neither to see nor listen to his arguments and to disparage, without evidence, his professional expertise. And that is pretty much how, spurred on by the most disreputable Press in the Western world, Britain has reached the present ridiculous position. However, if anyone wishes to see further into May's rigidly unreal position Dougan's analysis of her Lancaster House (Article 50) speech can be found here
https://www.youtube.com/watch?v=fhB-meWAmxI - and John can do the electronic equivalent of sticking his fingers in his ears with that as well.
For reasons which are a fundamental part of the EU's legal structure - reasons of which any signatory government must be aware - there cannot be the type of negotiation process, which, despite all evidence, the Tory government is claiming to be its intended 'strategy'. The election as a means to "strengthen the government's hand in the negotiations" is a simple and bare-faced fraud.
If May believes otherwise, she really is - in Nye Bevan's comment on Anthony Eden's dissimulation over Suez - "too stupid to be Prime Minister."