Robin Cook was sympathetic to hunting – though he had to be careful, given Labour’s fervent opposition to field sports.  Asked about his view, he once said that “I have never ridden to hounds”.  He paused before adding.  “But I have undoubtedly ridden horses that have been ridden to hounds”.

Cook’s reply may come in useful as we chew over reports that, as Cabinet discipline over Theresa May’s Brexit deal breaks down, David Lidington and Gavin Barwell are talking to groups of Labour MPs about a second referendum.

There would be nothing remotely wrong in the Prime Minister’s effective deputy, or any other senior minister, exploring how to get opposition MPs to support her deal.  If that includes peeling Labour MPs away from their leader, so much the better (at least as far as Downing Street is concerned).  Clearly, this is happening.

If, however, the conversation went on to mull furthering a policy to which the Government is opposed, the deputy in question would be in breach of collective responsibility.  As we write, neither Lidington nor Barwell have denied the claims.

Then again, collective responsibility at Cabinet level has broken down altogether.  Its members appear to have reached a consensus that May’s deal is dead in the water.  Only those who owe their Cabinet presence to her, such as James Brokenshire and Karen Bradley, are likely to pretend otherwise.  Otherwise, the top of the Party is dividing into two main camps.

The first includes Jeremy Hunt, Sajid Javid and the Cabinet Brexiteers who didn’t resign when May’s deal was presented to them.  Their view is that no deal preparations should be intensified, in the hope that this will convince the EU that the Government is serious about planning for it, and thus persuade it to offer real concessions on the Northern Ireland backstop.  If this doesn’t succeed, this group is prepared to embrace no deal.  Hunt has given an interview to that effect today, and Penny Mordaunt plans an announcement shortly.

The second includes Lidington, Philip Hammond, Greg Clark, David Gauke, and apparently Amber Rudd.  All opposed Brexit during the referendum campaign and, with varying degrees of enthusiasm, now conclude that the result cannot stand.  Some may have believed in the Prime Minister’s deal.  Others may never have done so.  But all are now reported to want another vote on it to take place soon, preparing the way for an “indicative vote” to take place on other policy options.  Again, these claims have not been denied.

This would duly find little support for no deal, and more for a second referendum.  The way would then be clear for turning that support into a Commons majority.

This helps to explain the ferocious infighting among Remainers and Soft Brexiteers about the so-called Norway Plus scheme.  Campaigners for a second referendum are trying to kill it off, in order to leave their plan as the only practicable option for that spectrum of MPs to back.  Nick Boles, the leading Conservative Commons advocate of Norway Plus, is fighting to keep it alive – and looking to Labour opponents of a second referendum to help him to do so.  If he fails, other MPs who have pushed the scheme, such as Oliver Letwin and Rudd herself, will find that a combination of their sympathies and events push them towards that second referendum.

Mention of cross-party conversations takes us back to Robin Cook.

Just as Cook never rode to hounds, so we can presume that Lidington will not be talking to Labour MPs about political realignment.  The Cabinet Office Minister may have been able to persuade himself that to discuss a second referendum with opposition MPs is permissible.  After all, May’s deal really can’t get through the Commons, as matters stand.  The Government must find an alternative policy.  Discussions about the possibility of a second referendum, he might reason, merely seek to find a new approach once the present one is exhausted.  But for such a lifelong Conservative – a Tory to his bones – to collude in discussing realignment would surely be several steps too far.

But just as Cook rode horses that had been ridden to hounds, so Lidington will be talking to Conservative MPs who are talking to Labour ones about breaking the party political mould.  Nicky Morgan has floated national government – though that is not quite the same thing.  Anna Soubry and Dominic Grieve have spoken of putting country before party, thus providing a mirror image of the European Research Group’s position.  ConservativeHome was struck by the airy way in one which one prominent backbencher told us recently that he is already assuming that the present party system will break up, and baking that calculation into his thinking.

This takes us to Theresa May.

The Prime Minister is hostile to both Norway Plus and a second referendum.  But there is a difference between being opposed to a course of action and never taking it.  The Sunday Times claims that she recently “war-gamed her options during a recent conversation with David Cameron. Her predecessor told friends that May – while personally opposed to a referendum – was a “servant of the Commons” and would back a second vote if MPs voted for it”.  This site has had the same reasoning put to it.

Up with this the ERG, and a big swathe of the centre of the Conservative Party, would not put.  Some of its members would again seek to bring down the Prime Minister.  This would arguably be as likely to produce a general election as a leadership contest, now that the option of a ballot of confidence in that leadership is not an option for a year.

One of the main reasons why the SDP failed was because, under our first the post electoral system, challenges to the established parties from the bottom up face formidable obstacles.  This might be less true of change from the top down.  In a general election under the circumstances we describe, May would control the Party, the money, the manifesto – and, ultimately, the selection process.  ERG members and some other Conservative MPs would not support a manifesto committed to a second referendum.

Is it too speculative to imagine a Tory Party which has lost those MPs – and much of its activist base – but gained a mass of Blairite ones?  And then to go on to think of the Party changing its name to reflect this development?  And of any new rival right-of-centre party having to set up from scratch, without a durable claim to the Party’s name, infrastructure or assets?

Perhaps.  But these are strange times.  And building an SDP Mark Two from the top down – in which Gavin Barwell would end up rubbing shoulders with Alastair Campbell, Rudd with Yvette Cooper, Lidington with Chuka Umunna and, yes, May with Tony Blair, as the Evening Standard smiles on – would be a great deal easier than doing so from the bottom up.

To those who say that all this is far too fanciful, we quote not Cook, but Erasmus – as we gaze on the hatreds consuming the Conservative Party, and bubbling away within Jeremy Corbyn’s Labour.  Erasmus was contemplating those tearing apart the Church.  “The long war of words and writings,” he observed, “will end in blows.”