There's been much jubilation at Nicola Sturgeon's resignation as First Minister of Scotland and leader of the SNP, particularly from the Labour party.
Their assumption is that with Sturgeon gone, of course Scottish voters will "come back" to Labour, like homing pigeons. But how realistic is that?
Usually when a party leader changes, that party's supporters broadmindedly think, "Let's give the new leader a chance to show us what they can do".
It's only when the new leader disappoints, that they look elsewhere. And when they look elsewhere, it's usually to a new party, rather than a party they'd voted for before.
Scotland in the last 20 years has been instructive. Some voters who were disaffected with Blair's Iraq policy switched to LibDem in 2005 and 2010, and then made the leap to the SNP in 2015. Some of those protest LibDem voters switched to Tory in 2017, as they'd voted for Brexit.
You see the same pattern in England: disaffected Labour voters switching to UKIP in 2015, and then switching to Tory in 2017 and 2019. Now some are flirting with the Reform Party, some are saying they won't vote.
The big thing in the next election will be the behaviour of those currently saying, "Don't know". Some of them are shy supporters of existing parties, some are genuinely looking for something new.