Oliver Lewis, the man who led Boris Johnson’s “Union Unit”, the department tasked with keeping the UK together, has quit the job after just two weeks, and, while that’s definitely not a great look for Number 10 (“the disunited Union Unit”), his appointment was probably a bad idea from the start. Putting a Brexiter in charge of taking on Scottish nationalism is like putting Donald Trump in charge of fact checking or Laurel and Hardy in charge of piano removals. It’s a recipe for disappointment, and chaos, and broken pianos. Not a good idea.

The theory, possibly, was that, as a veteran of Vote Leave, Mr Lewis would know how to fight a dirty trench war against other nationalists, and it’s certainly true that the Leave campaign won in 2016. But significantly, it did not win in Scotland. The Scottish nationalists also lost the referendum in 2014, so it would be fair to say, I think, that there’s no real evidence as yet that an aggressive, highly-charged, emotionally-led, fact-lite campaign would necessarily win a referendum in Scotland, however well the SNP does in May.

So, what would work? Mr Lewis is said to have favoured the combative approach – knuckle-dusters and knives rather than love bombs – but we should remember the ground that the two sides in the campaign are fighting over. Around 40 per cent of voters in Scotland appear to be committed to Yes and around 40% are committed to No, which means that, much like last time, the campaigns are fighting over the middle ground. The question the people at the Union Unit need to ask themselves therefore is: what sort of tactics will work with those sorts of voters?

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I think the answer – and here’s where I’d like to offer a little bit of friendly advice to the Union Unit if I may – is to focus tightly on who those middle-ground voters are likely to be. They’re likely to be more cautious, they’re likely to worry about the consequences of change, and they’re probably much less aggressive about their opinions, so you’ve got to ask what’s likely to convince them. Aggressive, jingoistic, Brexit-style campaigning? Or something much calmer, and more reasoned, and – dare I say it – more caring?

I know, of course, that there are many unionists who will vehemently disagree with this, and there are definitely sections of the No campaign that have been saying for a while now that unionists need to be more aggressive. For the moment, those voices are mostly at the grassroots level, although Ruth Davidson also said the mistake unionists made after 2014 was that they failed to “put the boot in”. But maybe Ruth and the others have forgotten that aggression is not the same as passion and maybe that’s the difference we need to get to grips with here.

What I’m saying is the strategy of the Union Unit should be to deliver a calm, informed case – to fact-bomb rather than love-bomb. I’m also saying that part of the problem with having a Brexiter like Mr Lewis in charge is that the Unit needs to take on the Brexit-style assertions of the SNP. The SNP, like Vote Leave before them, says an independent Scotland will develop strong trade links with other countries to replace trade with the rest of the UK; it also says there will be frictionless borders after independence. But Vote Leave said the same things about Brexit and Mr Lewis is maybe not the best person to point this out and expose the SNP’s Brexit-style promises.

We also shouldn’t underestimate the power of the fact bombs. An independent Scotland would have to make difficult economic adjustments (ie austerity). Using the pound outside the official sterling zone would be a massive risk (eg higher interest rates). Rejoining the EU as an independent country would lead to an increase in trade costs with the rest of the UK and the end of frictionless borders. And the personal income of Scots is likely to be affected. All of those uncomfortable little facts, delivered calmly and consistently, can have an effect on middle-ground voters.

There’s always a danger, of course, of going too far, catastrophising an independent Scotland, and thereby risking a backlash, but the way you deliver the facts, and the tone of the campaign, is crucial. One of the wisest moves by the unionist side in 2014 was to settle on the slogan “no thanks” (borrowed from “non merci” in the Canadian referendum of 1980). It contrasted with the more strident and aggressive Yes side and struck the right tone for less committed voters caught between the flag-wavers. There’s also something to be learned from politicians like Turkey’s Ekrem Imamoglu, who’s managed to push back against the nationalist populism of President Erdogan by consciously focusing less on identity. You cannot fight polarising populists, says Imamoglu, by being polarising yourself.

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In the end, this raises some serious problems for the Union Unit. Someone like Oliver Lewis was almost certainly not the right man to understand and implement the kind of nuanced, informed, and balanced campaign that’s needed to take on the Yes side. But then it’s hard to think of anyone in the UK Government who could pull it off, including (and maybe especially) Michael Gove. As for Boris Johnson, he is an asset to the No campaign as long as he doesn’t say or do anything.

Interestingly, the more reasonable wing of the Yes side also realises how this battle is going to be won. Nicola Sturgeon said last year that the Yes side had to show voters they understood the “complexity of the issues” and that the case had to be made with “patience and respect”. You can judge for yourself whether she’s passed that test, but the formula still stands. Neither side will win by getting angry (the angry types have already made up their minds anyway). And my advice to Mr Lewis’s successor at the Union Unit is that you cannot get all Brexity on the SNP, or out-nationalist the nationalists. Just keep saying the same things, calmly and politely, like “no thanks” and “have you seen these facts?”

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