2015's dim-sum index has too many courses

The guess was that the Tories would be ahead by three seats – then the stir-fried chicken arrived

Peter Mandelson first resigned from the cabinet on 23 December 1998 (Getty)

The Peter Mandelson Memorial Dim Sum Dinner is the British equivalent of the Iowa straw poll: the earliest harbinger of the next electoral cycle. It is a gathering that started on 23 December 1998. A group of my friends were lunching in Soho when news came through – on our pagers – that Mandelson had resigned from the cabinet. By coincidence, the same group of my friends were lunching just after Christmas two years later, on 24 January 2001, when Mandelson resigned again.

So, we made it an annual event, around this time of the year, and its main business consists of predictions for the year ahead. This year's, the week before Christmas, was dinner rather than lunch, but the business was the same.

Last year, we didn't do badly. Our average prediction for the Scottish referendum was a "No" vote of 56 per cent, compared with an outcome of 55.3 per cent. We were less secure on the European elections, the majority having predicted that Labour would win the most votes, although there was a minority for Ukip, which in the event won 26.6 per cent to Labour's 24.4 per cent.

This year, it proved harder than ever to pin people down to predictions. After some bullying, estimates for the most important number, the difference in seats between Labour and Conservative in the general election, were forthcoming. The average guess was that the Tories would be the largest party by three seats. Until, that is, the second round of stir-fried chicken arrived, at which point one member changed his mind and the average estimate shifted to the Tories being the largest party by five seats.

There was then confusion about whether David Cameron or Ed Miliband would be prime minister after the election. It was not obvious that Cameron would be able to form a government if the Tories had only a few more seats than Labour, because he might need the Democratic Unionist Party as well as the Liberal Democrats in order to have a majority in the Commons.

In any case, we were not sure that the Lib Dems would vote for the critical measure in Cameron's Queen's Speech, namely the EU referendum promised for 2017. Nick Clegg has positioned himself carefully, saying a year and a half ago that an in-out referendum was a matter of "when not if", but would his party be with him? His MPs would be reluctant in any case to prop up a Conservative government for a second term; and even more reluctant if the Tories had lost seats; why should they, in addition, vote for a referendum that might take Britain out of the EU?

On balance, therefore, the consensus favoured Miliband, although he was thought likely to need the Scottish Nationalists to get him over the line, which holds its own complications. The average estimate for the number of SNP seats was 18, which is three times as many as the party has now, but a long way short of the 54 suggested by recent opinion polls of Scotland.

The dim-sum forecast has shifted over the years. Two years ago, the meeting was unanimous that Cameron would be prime minister again. Last year was a split verdict: the majority for Cameron, a minority for Miliband. Now we have gone right over. Even I, with the highest Tory prediction – 20 seats ahead of Labour – wonder about the viability of a minority Tory government (on condition of an EU referendum), let alone of a second coalition.

To the rest of the business. Our average guess was that the Lib Dems would win around 30 seats, roughly halved from 57 last time, and that Ukip would win three.

If Miliband were prime minister, the majority favoured Boris Johnson as the next leader of the opposition, with a minority for Theresa May. If, on the other hand, Cameron were prime minister, he would have his referendum, which we thought would result in our staying in the EU. He would thus go down in history as a 10-year prime minister who won three referendums to keep things as they are: the voting system, Scotland and the EU. A conservative, in other words.

If Cameron stayed at No 10, the most popular view was that Yvette Cooper would be leader of the opposition, although there were minorities who predicted Chuka Umunna and Stella Creasy. The Creasy theory runs thus: if she can secure the 40 or so MPs' nominations that she needs, and she has been working on them, she is popular enough among the party members who would make the final decision.

The meeting considered the Andy Burnham theory – that "We Heart NHS" is an irresistible slogan among party members, and that he might stand with Rachel Reeves as his deputy and shadow chancellor candidate – but the gathering was unimpressed.

Then, as it always does too soon after a political debate, the bill arrived.

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