Clarke was assistant to Claudio Ranieri, Jose Mourinho, Avram Grant and Phil Scolari at Stamford Bridge, before becoming Gianfranco Zola’s right-hand man at West Ham.
Clarke said: “I could have done the job. Every other year it seemed someone else would come in as manager and there was a danger I would always be labelled as Chelsea’s No 2.
“I don’t think anyone thought they could pick up the phone and ask if I was interested.
“Chelsea were very surprised by my decision, that’s why they made it so difficult for me.
“They refused to accept my resignation at first but I understand why they did it.”