Just breaking on the BBC news website now. It appears that the higher-ups at CEOP didn't want to be assimilated as part of the National Crime Agency and so the boss has fallen on his sword so to speak.
The Home Office confirmed the Home Secretary was aware Jim Gamble had sent a resignation letter to her.
The agency said it did not feel it was in the best interests of children and young people for Ceop to be assimilated into the National Crime Agency.
The merger proposal was outlined by Theresa May in July.
Ceop told the BBC it "does not feel that it is in the best interests of children and young people for CEOP to be assimilated into the National Crime Agency, as was announced a short while ago.
"This direction of travel does not seem to have changed and Ceop's CEO, Jim Gamble, has therefore offered his resignation to the Home Secretary with a four month notice period. We are not prepared to comment further."
It is understood that Ceop has made representations to the government since the announcement that its work was to become part of the proposed National Crime Agency.