The big problem for Labour is that they're playing the popular vote game rather than the constituency one. Starmer is bound to give them landslides in London and university cities but judging by what happened in Hartlepool and Tees Valley they might actually really lose the north for the first time in 2024. In effect, having fewer seats than the Tories if the NW, NE and YH are combined. The NW is still going to be Labour because of GM and Merseyside but along with urban Yorkshire and Newcastle these areas are set to be red islands in a sea of blue if this keeps up.
Now Labour have abandoned the economic populism that still rendered good numbers in the rural north in 2015 then okay in 2017 and now appear to be fishing for Lib Dem voters and suburban Tories more than anything else. Their problem is that unlike in the US, suburban voters departing the right-wing can choose red or yellow in Britain and vote splitting will be a serious issue in more than one place.
They're stuck between a rock and a hard place. I looked at the London Tory constituencies and there's no reason why Labour can't pick up 8-10 of those in the next election. The problem though is that at the same time the Tories may pick up even more than that considering there are nine seats in Barnsley, Chesterfield, Doncaster, Hull (E & W), Rotherham, Stockton (N), Sunderland and the final remaining seats in Walsall (S) and Wolverhampton (SE) where the Labour vote share is crash landing. That'd mean all those gains are offset immediately. Then add that Yvette Cooper's seat along with other rural mining belt areas are destined to go the way of Bolsover sooner rather than later and the results are obvious. There are also specific "Brexit seats" in Bradford (S) and Sheffield (SE) in danger.
Unless Labour find a way to balance economic leftist populism without falling down the Momentum path they are in a hopeless spot. Already in 2017 the required PV lead for the Tories to gain a majority was at 4 points and that will further lower in the future at this rate. Especially if Scotland leaves. If that happens then the Tories might lose the PV and still gain a majority like Labour did if England was a separate entity in 2005. Actually a landslide in spite of fewer votes! (
https://en.wikipedia.org/wiki/2005_United_Kingdom_general_election_in_England)
That's another big elephant in the room: if Labour win power it will be through a confidence and supply deal with the SNP for a minority cabinet and a triumphant Sturgeon would then be more likely to win the referendum if Scottish Labour unionists have been thrown under the bus by the Prime Minister. Then Scotland get independent in the middle of parliament and a Tory PM gets installed by default.
From a political strategy standpoint Labour are in a deep trap right now and it's very hard to see it ending well for them. The Tories control the constituency boundaries and they won't change what works for them. They are also doing it in the very core areas that carried Blair in three elections back when much of the Midlands and nearly all of the north were safe Labour territories.
Some people here are bullish about Labour going on the attack in the south, but let's be honest here. The south is right-wing economically when outside of inner cities. There's a reason Lib Dems have done better than Labour in those areas in the past. Reading West to go Labour eventually? Probably. Still, looking at Labour getting battered in both seats in Bournemouth and having lost Stevenage by 15 points last time is a reminder of how far they have to climb in the south to make up ground. They can gain some in between Brighton and Southampton but besides that there's not much in the south to pick up.