Starmer faces a difficult summer

Like Covid data, polling data has a built-in time lag of several days. Those sifting the evidence on coronavirus typically expect to see about a four-day lag between someone becoming infected and them showing up as a positive case after getting tested. Indeed, the Financial Times has just produced a graph showing distinct Covid case spikes among young men four days after every England football match in the recent European championships.

Opinion pollsters would recognise a similar lag when it comes to events that influence the standing of parties. It takes time for those events to percolate through the public consciousness.

So the latest rash of opinion polls, which are often referred to as a ‘snapshot’ of the public mood, actually reflect the public mood at the tail end of last week rather than right now. This amounts to ominous news for Keir Starmer, who may today be confusing himself with someone successful.