It’s part of the persona of “Boris Johnson” that Alexander de Pfeffel Johnson plays. It works wonders at ingratiating him with all walks of life. Makes him seem bumbling and unthreatening.
Don’t be deceived, this is a sociopath who knows exactly what he is doing.
If you have the time, this is the most illuminating thing on the man I have ever read, but be sure to read it to the end.