In Chapter One, why does Stilton take issue with Bertie having a drink in the novel, Jeeves and the Feudal Spirit?

In Chapter One, Stilton arrives and sees Bertie is having a drink which displeases him. Stilton has drawn Bertie's name for the annual Darts sweep at the Drone's Club and so stands to win money because of Bertie. For this reason, Stilton takes a judgmental interest in Bertie's conduct.