The 2026 local elections are upcoming! ~5000 councillors in local councils are going to be up for election, 2000 of whom are currently members of the Labour Party. It's possible that this will be an indicator of whether the Labour Party is actually doing okay, or if they need to try a different strategy.
The reason for the condition is to try to make the market causal on Starmer leaving, by screening off the evidential correlation that Starmer is more likely to stay on if Labour is doing well.
The complement conditional on Starmer leaving is
This resolves N/A if Labour doesn't lose over 1000 council seats (either it loses less than 1000 seats, or it gains seats), or if Starmer leaves in 2026 specifically.
1,000Presumably this market resolves as "N/A" if Labour loses <1000 council seats, or gains seats, or Starmer is no longer the prime minister before the election.
@AlanTennant Not by the next election; if Labour loses over 1000 council seats but Starmer only leaves in 2027, that would meet the conditions.