Starmer *is* a Corbynite. He's pursuing a Blairite agenda now because he has no choice. And the Blairite agenda hasn't changed since 1997. People wanted change in 2010. Instead they got "the heir to Blair". They voted for change in 2016 and again in 2019. They're still waiting for it to happen.

Sir Keir's problem is that he's trying to pursue a Blairite agenda with a Corbynite party. The mentality of the Campbell era was that the bigger the majority the more "moderate" Labour would be. Now the reverse is true. Their majority is so vast that the party is completely out of control.