With the battle lines drawn, an old warhorse of a quotation can probably be trotted out. To paraphrase the apocryphal words of the Duke of Wellington, I don’t know what effect David Cameron will have on the Brexit enemy, but by God, he terrifies me.

This is not because the Prime Minister is particularly fearsome. Instead, it’s the realisation that the campaign to remain in the European Union might be in trouble before it starts simply because of the man at its heart. The ducal echo is of the Grand Old Duke of York, not the victor of Waterloo.

There are other complications. What Mr Cameron wants, or says he wants, in the way of EU reform is not what I want. The future he foresees for the United Kingdom is not a future I would welcome. His claim that he would support withdrawal from Europe if he doesn’t get his way offers nothing, in my book, beyond grounds for a second Scottish referendum.

For now, nevertheless, an ill-assorted bunch, of which I’m one, are roped together in the belief that EU membership is a better idea than the alternatives. Many trade unions, most businesses, a majority within the SNP, Labour and the Liberal Democrats, others besides: it’s not what you would call a united front. It requires no faith in Mr Cameron, or in his daft “renegotiation”. But there he is, purporting to lead.

Such, as we know, is the nature of a referendum. Nuance is lost. Shades of opinion disappear as the binary logic grinds on. There is a world of difference between hoping for an independent Scotland managing its own European relationships and Mr Cameron’s attempts to manage his truculent Little Englanders. But here, for now, is where we are: the EU, for or against?

That being the case, you can only look upon this Prime Minister and despair. The tactics are woeful, the strategy mistaken. Even his letter yesterday to Poland’s Donald Tusk, President of the European Council, is the mark of a man who has decided to commence battle by offering hostages.

Mr Cameron has chosen exactly the ground on which sceptics want to wage this contest, in part by conceding their arguments, in part by omitting issues they will place front and centre in their campaign. The four areas for negotiation described by the Prime Minister are a sceptic’s dream of an easy early result.

Protecting the interests of “non-eurozone countries”, meaning the UK? This panders to the sceptic belief that “Europe” can be a pick and mix, that a semi-detached (or “sovereign”) state can have any kind of special relationship it likes without any of the responsibilities. Mr Cameron has put pure self-interest at the heart of his appeal. The EU does not, at least some of the time, work that way.

“Improving competitiveness”, otherwise known as serving the corporate interest? It would not occur to the Prime Minister that what he would call a business-friendly EU is not calculated to appeal to many ordinary voters. The Union is already subservient to powerful interests; he would have it bend a little more and degrade workers’ rights. Sceptics will meanwhile simply welcome proof that, in their terms, the EU is not working.

An opt-out from “ever-closer union”? This is a red herring. If Mr Cameron is suggesting that the UK is not already fully-protected against such a development he is being dishonest. No doubt he can alter the wording of a treaty but reality will remain unchanged. If he is serious about “strengthening national parliaments”, meanwhile, the Prime Minister is seeking more than other member states can or will concede.

The same goes for access to benefits and EU migrants, in or out of work. Mr Cameron means to control the free movement of citizens, a right he maintains is being “abused”. His European partners won’t wear that, meaning they won’t wear interference with in-work benefits. Free movement is fundamental to the EU and fundamental, whether the Prime Minister grasps it or not, to the free market he is supposed to value. Sceptics will retort, simply, that this is no way to deal with immigration.

Yesterday they were already hammering away. Predictably, Ukip’s Nigel Farage charged that Mr Cameron had promised nothing that would restore Westminster’s sovereignty, nothing that would end free movement, and made no attempt to reduce the UK’s contribution to the EU budget. This happened to be more or less true. But it was also an indication, if one was needed, of where the campaign for withdrawal is heading.

The Prime Minister has tried to present re-negotiation as a mere technical exercise, not a profound choice about the kind of country in which people hope to live. Even his apparent openness to the possibility of withdrawal is a sham. Sceptics will never believe it. Anyone else, asking what might follow, can whistle for an answer. On yesterday’s evidence, Mr Cameron has no idea.

He has seemed to rule out the “Norway option”. He has dismissed Swiss arrangements as a matter of costs without benefits. The sole remaining model is Turkey, which enjoys little more than a customs union with the EU. In his own terms, therefore, Mr Cameron has entered the fray without a credible threat as to what might follow if his demands for improved terms are rebuffed.

The question of treaty change meanwhile hangs in the air. The Prime Minister presents it almost as a minor matter, a bit of altered wording nodded through by like-minded people. That flies in the face of EU history. Such changes tend to involve huge upheavals. For that reason, far less for reasons of principle, there is little appetite to begin rewriting rules simply to allow Mr Cameron to calm his backbenchers and roll back Ukip.

It is easy to forget what is at stake. These manoeuvres will lead to a vote. That vote could see the UK stumble out of the EU for entirely trivial reasons. Real reform, for which there is a pressing need, will become a lost cause while Mr Farage shouts the odds, Mr Cameron dissembles, and Tory eurosceptics pursue their fantasies. Scotland will then have its choice to make, but nothing about that should be taken for granted. We could still be out of the EU for an unspecified period.

Mr Cameron made a fundamental error yesterday. Attempting to hedge his bets, he gave eurosceptics all the ammunition they could want. The Tory MP Peter Bone stated their case when, sardonically, he thanked the Prime Minister for making it clear that political union and free movement would survive renegotiation. With that established, said Mr Bone, it was clear the UK should leave the EU.

The Scottish National Party is wary of the word unilateral. Nevertheless, Mr Cameron’s performance might have left Nicola Sturgeon with no alternative other than to restate her Government’s position. It might amount to declaring that Scotland will remain in the EU no matter what. Then we’ll see what eurosceptics mean when they talk about Britain.