In the run up to every set of May elections when there isn’t a General Election I write a guide to what constitutes success for Labour.

This year I am able to look back at the benchmarks I set for Ed Miliband in the equivalent set of elections in May 2012, to ensure that I suggest targets for Jeremy Corbyn that are comparable – though of course we now know based on the defeat in 2015 that the electoral cycle means that the Labour Party needs to do a lot better now than it was doing in the mid-term of the 2010-2015 Parliament in order to win in 2020.

To try to see through the inevitable Tory spin about how many gains Labour should make it’s important to look at the previous results for these sets of elections and compare with them.

What we should really be interested in is the direction of travel for Labour.

The headline election for the media is obviously the London Mayor election. Winning it is both an immense boost to momentum for the next General Election, and puts your party’s hands on some real levers of power, though in a limited range of policy areas. Given the extent to which it’s a personality battle between Sadiq and Zac, with the other parties squeezed out, it’s of limited value as a proxy for how the parties might perform in a General Election. In the past Ken Livingstone out-performed the national Labour brand, now the polls suggest the same for Sadiq Khan.

A more accurate indicator of Labour’s support as a party in London will be the London Assembly poll. The 2012 election was Labour’s best result ever for the Assembly, winning 12 seats. Holding all these seats would be a significant achievement. This would mean holding the two constituency assembly seats gained in 2012 (Camden and Barnet and the ultra marginal Ealing and Hillingdon) and our London-wide vote share holding up so we still got four top-ups seats.

Any additional gains in the constituencies (Merton and Wandsworth or Havering and Redbridge are the potential targets) would likely be offset by receiving fewer top-up seats as the electoral system keeps the overall result broadly proportional. Even a loss of one seat to the Tories would still look like a victory as it would leave Labour on 11 seats and the Tories on 10. It would however indicate Labour going backwards compared to the Ed Miliband era in the region where Corbyn is probably most popular and where the largest influx of new party members has bolstered an already powerful campaigning force.

In the Welsh Assembly elections Labour holds exactly half the seats – 30 – leaving us one seat short of an overall majority. Holding those 30 seats would be a good achievement given the 2015 General Election result in Wales was poor. The additional member system voting should help as it may offset constituency losses with regional top-up seats.

In the Scottish Parliamentary elections the scale of Labour’s wipeout to the SNP last year means the only reasonable benchmarks are to avoid coming third to the Tories in vote share or number of seats and, as a bonus, morale would be boosted if we could retain at least a single constituency seat, and not be entirely reliant on proportional top-up regional list seats.

For the English council elections the key question is whether Labour can hold control of the winnable major southern towns that it symbolically gained in 2012: Exeter, Southampton, Reading, Harlow, and Norwich. We should also be looking to gain back Plymouth, Thurrock and Great Yarmouth from No Overall Control as we won control there in 2012 but subsequently list it again. Other key defensive councils we currently control include Carlisle, Rossendale, Crawley, Cambridge, Derby, Lincoln, Dudley and Cannock Chase. These are all places we need to win in a General Election to form a government. Labour might also be able to take overall control in Newcastle-under-Lyme and Walsall.

There are at least four ways of measuring Labour’s national performance: national vote share, raw number of councillors, number of councillors gained and number of councils controlled.

Looking first at national vote share, the estimated figures the BBC uses are as follows for previous years in this cycle:

1996 43 per cent Labour share of the vote

2000 30 per cent

2004 26 per cent

2008 24 per cent

2012 39 per cent

We need to be getting around 37 – 39 per cent just to be in the same place we were in 2011 and 2012 under Ed, which wasn’t enough to win the subsequent General Election. If we exceed that we almost certainly beat the Tories on vote share too.

Raw number of councillors is the national (GB) total figure including all the thousands of councillors not up for election.

1996:10,929 Labour Councillors (the highest number ever)

2000: 8,529

2004: 6,669

2008: 5,122

2012: 6,559

Currently Labour has a total of 6,875 councillors. We need to not be building on this total at this stage in the cycle because previous cycles tell us that over the life time of this parliament we need to get to over 8,000 if we are going to win a General Election.

Number of gains. For comparison here are the years since Thatcher came to power when Labour has made net gains (in the other 18 years not listed, we lost seats):

1980 +601 Labour councillors

1981 +988

1983 +8

1984 +88

1986 +13

1988 +76

1989 +35

1990 +284

1991 +584

1993 +111

1994 +44

1995 +1,204

1996 +468

2010 +372

2011 +860

2012 +847

2013 +288

2014 +256

The only non-General Election years in which Labour has lost seats while in opposition were 1982 (the year of the Falklands war) and 1985 (the year of the miners’ strike). As explained above we need to be making net gains this year to move us from the current 6,875 councillors to the 8,000 we need by 2020 if we are going to win a General Election. We lost 203 councillors on General Election so gaining back that many would at least restore us to our 2014 position.

Control of councils is a lagging indicator because the practice of many councils electing only a third of their members each year, including this year 32 of the 36 Metropolitan Boroughs where Labour is strongest, delays and softens political trends.

The number of councils Labour has controlled has been as follows:

2002 – 136 (this was the last year in which we controlled more than the Tories)

2003 – 103

2004 – 94

2005 – 92

2006 – 75

2007 – 58

2008 – 46

2009 – 37

2010 – 54

2011 – 81

2012 – 114

2013 – 118

2014 – 122

2015 – 119

We need to stay in the range we have been in since 2012 – over 114 councils controlled, in order not to be out of the game in 2020, though it needs to be repeated we didn’t win in 2015 despite holding this many councils.

The location of councils and seats gained is important too: we need to make gains in councils covering areas similar to seats we lost in the 2010 General Election when we lost power.

One final indicator won’t appear in the media headlines but is worth looking through the detailed results for: the Labour seat gains in councils where we have been reduced to a handful of councillors or none at all. These will be a good indication of whether Labour is truly back on the map as a party with nationwide appeal and whether the doubling of party membership is bringing Labour back to life in previously moribund areas.

I have covered the Police and Crime Commissioner elections and suggested that given these were a rather miserable set of low turnout results in 2012, we need to be making significant progress compared to then – net gains, and overtaking the Tories to have the largest number of PCCs.