During the election campaign a blue envelope was delivered to my home from the Lord Chancellor, marked on the front “The Lord Finkelstein, Writ of Summons”. Inside was a document issuing what was in capital letters described as a COMMAND.

“The weightiness of the said affairs and imminent perils considered (waiving all excuses) you be at the said day and place personally present with Us and with the said Prelates Great Men Great Women and Peers to treat and give your counsel upon the affairs aforesaid”. Well, seeing as the Queen put it like that, I didn’t have much choice, did I?

So last week I duly attended (was on the said day personally present as I am now going to put it when I next go to dinner in Radlett) the House of Lords and was sworn in, pledging allegiance to Her Majesty. And I found it, as I always do, a moving occasion.

Well actually, not just as I always do, more than that. A couple of peers looked at me oddly when I said it was moving, regarding it as a boring administrative task, so I told them it was because my Mum attended the first time I did it and they understood. I decided not to go into the other part of it. I was moved because right at this moment I feel particularly happy about being a subject of Queen Elizabeth II and especially pleased to be pledging my allegiance.

The last few years have been a peculiarly grim time for Jews in politics. Most of us have scarcely been able to believe that antisemitism has become such an issue. And we haven’t been able to shake the fear that it wouldn’t matter to other people. That we were too few and people too oblivious for it to make any difference. So I was moved on the day of taking the oath by the thought that we were not too few, and people were not too oblivious, and it did make a difference. The British people proved themselves true friends. I accept their COMMAND. I pledge my allegiance.

There were strong reasons to think that antisemitism wouldn’t have any impact on the election. People don’t follow politics too carefully, they don’t know any Jews, they don’t know what antisemitism means, there are plenty of other issues. And yet the evidence, both anecdotal and statistical, is that the effect on the result was real.

So why this impact? Well, first it was because people had begun to suspect that Jeremy Corbyn wasn’t very competent or much of a leader. His unwillingness or inability to deal with what was clearly a troubling issue bewildered people. Many imagined that he would wish to sort out the problem if he could, so they just assumed he lacked the strength and leadership qualities to do it. So even for those who neither knew what antisemitism was or cared, the issue reinforced doubts they already had about Labour’s leader.

Then there was the weirdness of Mr Corbyn’s position. How could a Labour leader and Labour members be accused of racism by someone like the Chief Rabbi? Antisemitism, uncomfortably in some ways, was one of the parts of his unconventional positions on foreign and domestic policy that seemed to cut through, that struck a chord. People could perceive that, whether or not it mattered by itself, it pointed to something bigger. That Mr Corbyn’s leftism departed from the norm, and not in a good way.

But finally, and in a way that was very affirming and very encouraging, people did, in the end, turn out to understand and to care about racism against Jews. A year out from the election, it seemed they did not. They struggled with the word, they were pretty disengaged from politics anyway. But as the election approached pollster friends began telling me that it was coming up in focus groups.

Liberal minded people, particularly in the south, many of them not Conservatives at all, began to say that it made it hard for them to vote Labour, even tactically. And further afield voters cited it when explaining why they found Jeremy Corbyn off putting.

It was only one issue. But it mattered. We mattered. And sure, many millions voted Labour anyway. But my Mum always taught me not to look at the Emmental and see only the holes.

Daniel Finkelstein is Associate Editor of The Times