RACHEL JOHNSON: Just stop picking on my big brother! (But, sorry Boris, I'm still voting In) 

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'If your brother takes us out of the EU, I’ll never forgive him.’ I’m hearing this a lot, and not just from randoms in the street. My husband, Ivo, starts up from the moment the Today programme comes on to the midnight news and Sailing By.

After a while I said – with, I felt, admirable calmness under the circs – that if he wants our marriage to survive the referendum, it’s probably best that we don’t talk about Boris.

I should explain that Ivo and Boris get on like a house on fire – what a strange but apt phrase that is – but they do have form.

Standing by my sibling: Rachel is outraged at the attacks on her brother, Boris. The pair are pictured with their father Stanley (left) and brother Jo (right)

Ivo is a zealous Europhile who once served as Boris’s foreign editor in the 1990s when he was filing from the capital of Europe for The Sunday Telegraph. My husband would complain to Charles Moore, then editor, that Boris’s pieces were over-egged, but Moore would insist they ran intact as they were such jolly super copy.

Close friends are refusing invitations to my kitchen suppers in case I have Brexiteers in the house. Or have taken to ringing up in advance to scope out who’s coming.

And everyone remarks, at some point, as if they are the first person in the world to have ever said this to me: ‘Gosh. It must be very… complicated around the Sunday lunch table right now.’ As if all Johnsons live together like the Waltons in some closed compound, only talking about the pros and cons of sovereignty and the qualified majority vote.

I liked what Boris said about the free movement of people being OK when we were six but not 28 member states, and I agree that – to get down to brass tacks – Article 45 of the Lisbon Treaty guaranteeing freedom of movement is no longer fit for purpose

The truth is, they’re not far wrong. The family hasn’t fallen out, amor vincit omnia, but it is correct to say that my former MEP father Stanley is chairing Environmentalists for Europe. My brother Jo is Science and Universities Minister and is campaigning for In too. Brother Leo and my three children are crossing the Remain box. Only Boris and his wife Marina are for Vote Leave (though Boris has claimed that the family harbours a ‘secret Brexiteer’).

So, yes, the referendum has divided country, party – and, in my case, split my family. We have blue on blue and we have Johnson on Johnson. And it’s split me down the middle too.

What feels like a lifetime ago – ie February – being a smug metropolitan member of what Michael Gove calls the ‘gilded elite’, I was firmly for Remain. I tried to ‘turn’ my brother over ready-made lasagne and tennis in the rain, as I said here in this paper at the time.

The environment, security, peace in our time, common cause as a continent in the face of known and unknown existential threats, Putin, blah blah blah, solidarity, trade, blah blah, not to mention the scaly line-up for Leave from George Galloway to Keith Chegwin, etc etc – it seemed to me then that any right-thinking person would be mad even to contemplate voting out.

Every time I looked at my daughter Charlotte, 22, a foreign languages grad whose dream is to work in Paris, I thought, this is not just ridiculous, it is bonkers that the older generation has even been given such a say over the future of our children and grandchildren for years to come.

And then the campaign started. The battle buses fanned out to all points across the country, the TV debates kicked off, the personal attacks started, and I admit: from that moment it’s been quite a ‘journey’.

I’ve changed my mind, and changed it back. In my case, I’ve been brought, like many millions of others by the Brexit campaign led by my brother, to the very brink of… indecision.

You see, I liked what Boris said about the free movement of people being OK when we were six but not 28 member states, and I agree that – to get down to brass tacks – Article 45 of the Lisbon Treaty guaranteeing freedom of movement is no longer fit for purpose, given the influx, and that the union could disintegrate under the pressures of external migration, the euro, or both. And I didn’t like it when Hezza came out and said my brother had lost the plot. I didn’t like it when Major said his campaign was ‘squalid’ and he was a ‘court jester’ and the PM dissed half the country as ‘Little Englanders’ and ‘quitters’. Or when fellow Tory Amber Rudd said Boris isn’t the man you want driving you home at the end of the evening.

I wince and I think of my parents, listening to these things being said about their son, in whom they are well pleased, and I mind (probably more than Boris does – water off a duck’s back).

It is at moments like these that blood feels far thicker than the 21 miles of water separating us from the Continent. My sisterly loyalty roars to the fore. I can’t help it. I want Boris/Vote Leave (the two are indivisible) to win and prove them all wrong, and serve them all right.

And then, and then… the red mist clears. There are only ten or so days to go, and still, everyone asks me whether I am an inner or an outer. I suppose they reckon that, if even Boris’s sister and most of his family disagree with him, the bookies are right, and he hasn’t got a hope. Mmm. Whatever you think, the arguments on the Brexit side have often been convincing and they have always been well made.

And however cross Cameron and the rest are with the Brexiteers, it is thanks to them that we have had a proper debate. It is thanks to them we have aired the issues ad nauseam. I understand that Dave may not see it like this now, but Boris and co have actually performed a valuable public service for the Prime Minister. It is thanks to them that if the nation does vote to stay in, however narrowly, the PM can come out on the steps of Downing Street and say that we have settled the issue for a generation.

Last month, I sat next to a Swiss man at a dinner. He runs a major gallery, and for him London is the centre of the international art world. We were talking about the referendum. To my surprise, Hans-Ulrich Obrist quoted Robert Frost. ‘Two roads diverged in a yellow wood, And sorry I could not travel both, And be one traveller…’

My brother Jo (pictured) is Science and Universities Minister and is campaigning for In too. Brother Leo and my three children are crossing the Remain box. Only Boris and his wife Marina are for Vote Leave (though Boris has claimed that the family harbours a ‘secret Brexiteer’)

What feels like a lifetime ago – ie February – being a smug metropolitan member of what Michael Gove (pictured centre with Boris and Crime Commissioner for Suffolk Tim Passmore) calls the ‘gilded elite’, I was firmly for Remain

It seemed to sum up my feelings for most of this campaign so well.

I wish I could take both roads. But I can’t and nor can you and, in the end, my feelings come down on this side. I think many of the arguments made by Vote Leave campaign have been right. But I think Brexit is the wrong answer.

This is not because the EU is marvellous. The reverse. It’s because the problems of Europe are so big that it would be a dereliction of duty if we – a big grown-up country – went AWOL at this point. We must not be the rats fleeing the sinking ship. So – confident in the knowledge that my stated preference will send many sensible people stampeding in the other direction – I am going to vote Remain, in the hope of three outcomes.

One, I hope Remain wins, but not big. Two, I hope that the EU realises after this hairy scrape that they need us more than we need them, and our fellow partners gratefully agree to hold an emergency intergovernmental conference to sort out migration and the free movement of people.

And three, I hope then Cameron – who always claims he wants his best players on the pitch – will be a good captain, and put in Boris as his lead striker in Europe, as the best way of speeding progress towards much-needed treaty reform after an ugly and bruising few months.

My husband, however, doesn’t believe me. ‘You will vote Boris because you have no politics at all,’ he raged at me as we watched the ITV debate, and I shouted down Amber Rudd’s below-belt jibes and clapped my brother’s final summing up. ‘You only believe in Johnsons.’

But I gave him my word he was wrong. Though no Remainiac, I will vote in. After all, membership of the EU is like marriage. You don’t leave a 40-year-old union over one tiff, even if it is your beloved big brother ordering you to go.