Professor of psychology Cary Cooper has said that David Cameron will be remembered for "screwing up", after the Prime Minister was heard humming as he walked away from announcing his intention to resign formally on Wednesday.
The Prime Minister was returning to Number 10 and his microphone was still on.
Cooper explains why he believes he sang the tune.
"You've had all the stresses and strains of the referendum," he explained. "It didn't go his way and it's somebody elses problem now, I can understand.
"Particularly leaders nobody ever appreciates them, they always look for the negative in what they did," he told The Two Mikes. "What they'll think unfortunately about Cameron, even though he did some really good things for the economy they won't remember any of that, what they'll remember is the referendum and how he screwed it up.
"[If you stay in power too long] something will go wrong, you'll be blamed for it and you'll leave in disgrace, it's much better when someone says that's it I've had enough.
"[People] don't think about it as the individual is aspiring to achieve the pinnacle of their career. Once you get there, what you really should do is reflect on it.
"The problem is once they get there quite a few of them want to hold on to it, they don't know when to let go."