The scale of Keir Starmer’s challenge at the next election is becoming clearer – it’s huge

Keir Starmer needs to do better than every Labour leader since the war – apart from Tony Blair in 1997 – just to become prime minister at the head of a minority Labour government in a hung parliament at the next election.

Now that the boundary commissions for England, Scotland and Wales have published the first draft of their proposals for new constituencies coming into effect in 2023, we have a clearer idea of the scale of Labour’s challenge. Thanks to analysis by Electoral Calculus, a brilliant public service, we know that the effect of new boundaries is to give the Conservatives about 13 more seats. Labour loses eight seats, the Liberal Democrats three and Plaid Cymru two.

The first thing to say about these changes is that they are fair, even if they may not seem like it to the parties that lose out. Population movement means that the electorates in Labour constituencies tend to be smaller than in Tory ones, which gave Labour an unfair advantage at the last election. Now, the independent commissions have tried to equalise constituencies to level the playing field.

The second important point is that these draft boundaries are not the final say. The commissions are open to suggestions to improve the choices they have made. But the end result is likely to be similar to this first assessment.

So, that means that wherever the finishing line for Labour was at the next election, it is likely now to be about 13 seats further away. Given how far away from victory Labour was before the boundary changes, this is bleak news for Keir Starmer.

We can now estimate reasonably precisely what Labour will have to do if Starmer is to have any prospect of emerging from the next election as prime minister.

First, let us look at the prospect of a majority Labour government. This seems so unlikely that we don’t need to spend much time on it. For Labour to have a majority of one, it would need 322 seats, if we assume that Sinn Fein continues to hold seven seats (there are 650 seats altogether, a number unchanged by this boundary review after the government abandoned David Cameron’s attempt to cut the total to 600; with seven Sinn Fein MPs not taking their seats, a party with 322 seats would have a majority over the 321 seats held by other parties).

To win 322, plus the eight lost in boundary changes, would require Labour to win something like 45 per cent of the vote, while the Tories would have to go below 33 per cent. This would be a swing to Labour from the previous election of 12 per cent, which is bigger than the biggest swing to any party since the war, namely the 10 per cent swing achieved by Tony Blair in 1997. That would seem to require something really quite dramatic to happen.

Previously, I have tried to cheer up Labour people by saying that the swing required for Starmer to become prime minister is actually much less than that.

“All” that Labour and other parties need to do for that to become possible is to deprive the Conservatives and their recent allies – the Democratic Unionist Party – of a majority. It is not obvious what the DUP would do in a hung parliament after the way Boris Johnson has treated them, but all the other parties have said that they would not prop up a minority Tory government. So, as long as the Tory/DUP total can be kept below 322 seats – after the Tories gain 13 from boundary changes – then Starmer is likely to become prime minister.

Unfortunately for Labour that would still require a 5 per cent swing, which is still greater than it has won at any postwar election apart from 1997. Apart from Blair, the biggest swing to Labour was the 3 per cent gained by Harold Wilson in 1964.

On the other hand, although history may warn against it, it doesn’t look unattainable. It would require Labour to pull within two points of the Tory share of the vote. Starmer could be prime minister even if Labour wins, say, 38 per cent of the vote while the Tories are on 40 per cent. Which, given the current average Tory lead in the opinion polls of five points, feels within reach – if enough bad things are blamed on the government over the next two-and-a-half years.