Parker v McKenna (1874–75) LR 10 Ch App 96 is a UK company law case, concerning the rule against having any conflict of interest.

It was arranged that the certificates would be withheld, the bank had a lien on the shares for the premiums and no transfer could be made till £30 was paid up.

James LJ made this famous statement: I desire to add but little to what the Lord Chancellor has said.

I do not think it is necessary, but it appears to me very important, that we should concur in laying down again and again the general principle that in this Court no agent in the course of his agency, in the matter of his agency, can be allowed to make any profit without the knowledge and consent of his principal; that that rule is an inflexible rule, and must be applied inexorably by this Court, which is not entitled, in my judgment, to receive evidence, or suggestion, or argument as to whether the principal did or did not suffer any injury in fact by reason of the dealing of the agent; for the safety of mankind requires that no agent shall be able to put his principal to the danger of such an inquiry as that.

I also say for myself that I agree in what has been said with regard to the dealings with the Fox shares, that I could not satisfactorily to my own mind have disposed of that part of the case upon the materials before us.