Today’s report from the Fabian Society makes for grim reading for the rump of the Labour Party which still cares about winning elections. The title, Stuck – How Labour is too weak to win, and too strong to die, gives a taste of how the Fabians view Labour’s electoral prospects.

Most starkly, the report foresees Labour falling below 200 seats on its current performance in the polls – even before taking into account the possibility that the Party will underperform compared to polling, as it tends to do. Their calculation would see 39 Labour MPs lose their seats.

It isn’t a perfect forecast, of course. They’ve come to their number by applying a uniform swing to every constituency, which doesn’t happen in real life. So in reality some marginal MPs could hang on and others with larger majorities could lose their seats. But even as a sketch estimate it’s a stark reminder to the PLP that their leader threatens to march them straight to the door of the Jobcentre.

It’s worth looking at the 39 MPs who have the smallest majority over the Conservatives. Some on this at-risk list are long-serving parliamentarians (Joan Ryan, David Winnick, Paul Flynn), others are supposedly rising stars (Rosena Allin-Khan, Tulip Siddiq) and there’s even a shadow cabinet member (Cat Smith):

1. City of Chester – Chris Matheson

2. Ealing Central and Acton – Rupa Huq

3. Brentford and Isleworth – Ruth Cadbury

4. Halifax – Holly Lynch

5. Wirral West – Margaret Greenwood

6. Ilford North – Wes Streeting

7. Newcastle-under-Lyme – Paul Farrelly

8. Barrow and Furness – John Woodcock

9. Wolverhampton South West – Rob Marris

10. Hampstead and Kilburn – Tulip Siddiq

11. Enfield North – Joan Ryan

12. Hove – Peter Kyle

13. Dewsbury – Paula Sherriff

14. Lancaster and Fleetwood – Cat Smith

15. Derbyshire North East – Natascha Engel

16. Harrow West – Gareth Thomas

17. Bridgend – Madeleine Moon

18. Middlesbrough South and Cleveland East – Tom Blenkinsop

19. Westminster North – Karen Buck

20. Walsall North – David Winnick

21. Tooting – Rosena Allin-Khan

22. Wrexham – Ian Lucas

23. Birmingham Northfield – Richard Burden

24. Wakefield – Mary Creagh

25. Gedling – Vernon Coaker

26. Eltham – Clive Efford

27. Copeland – Jamie Reed (resigned)

28. Stoke-on-Trent South – Robert Flello

29. Birmingham Edgbaston – Gisela Stuart

30. Clwyd South – Susan Jones

31. Coventry South – Jim Cunningham

32. Darlington – Jenny Chapman

33. Delyn – David Hanson

34. Blackpool South – Gordon Marsden

35. Alyn and Deeside – Mark Tami

36. Scunthorpe – Nic Dakin

37. Bristol East – Kerry McCarthy

38. Newport West – Paul Flynn

39. Southampton Test – Alan Whitehead

The profile of the seats involved is quite striking. Some have been held by Labour for decades, and many are in the classic Midlands and Northern heartlands where Labour found itself on the wrong side of the referendum. Precisely the kind of seats, in fact, which you could list under Nick Timothy’s Erdington Conservatism – and many of them located in the areas where CCHQ is recruiting campaign managers. The presence of Copeland on the list is a reminer that the forthcoming by-election is going to be a fascinating test of the state of play. A peppering of Welsh seats would also follow the recent trend of Tory advances there.

The usual caveats about national swing models must of course apply – in some places local factors or personal votes will be at play, and most importantly we don’t yet know how the Leave/Remain dynamic might shift votes between the parties – an unknown further complicated by UKIP and the Lib Dems racing to redefine themselves after the referendum.

The most obvious potential disparity is in the presence of a series of London seats on the above list. The Fabians themselves say that Labour remains strong “in urban pockets”, Labour’s activists are disproportionately in the capital, and Richmond Park suggests that some Londoners are willing to swing to a Continuity Remain candidate, so perhaps it would be an error to assume the London seats are as vulnerable as a national swing might suggest.

If they were removed, though, that would imply that a Labour overperformance in London might be masking an even worse underperformance elsewhere. If so, here are the ten next seats on the Lab/Con marginals list – and look how many of them fit the profile of Leave-voting, traditional working class electorates.

40. Chorley – Lindsay Hoyle

41. Bishop Auckland – Helen Goodman

42. Coventry North West – Geoffrey Robinson

43. Bolton North East – David Crausby

44. Hyndburn – Graham Jones

45. Bury South – Ivan Lewis

46. Wirral South – Alison McGovern

47. Dudley North – Ian Austin

48. Mansfield – Alan Meale

49. Batley and Spen – Tracy Brabin

50. Workington – Sue Hayman