Per Lord Campbell in Wilde v Gibson (1843) 1 HL Cas 605 at pp 632, 633:
If there be, in any way whatever, misrepresentation or concealment, which is material to the purchaser, a court of equity will not compel him to complete the purchase; but where the conveyance has been executed, I apprehend, my Lords, that a court of equity will set aside the conveyance only on the grounds of actual fraud.
Derry v Peek (1889) 14 AC 337, per Lord Herschell:
My Lords, in the statement of claim in this action the respondent, who is the plaintiff, alleges that the appellants made in a prospectus issued by them certain statements which were untrue, that they well knew that the facts were not as stated in the prospectus, and made the representations fraudulently, and with the view to induce the plaintiff to take shares in the company.
… I think it important that it should be borne in mind that such an action differs essentially from one brought to obtain rescission of a contract on the ground of misrepresentation of a material fact. The principles which govern the two actions differ widely. Where rescission is claimed it is only necessary to prove that there was misrepresentation; then, however honestly it may have been made, however free from blame the person who made it, the contract, having been obtained by misrepresentation, cannot stand. In an action of deceit, on the contrary, it is not enough to establish misrepresentation alone; it is conceded on all hands that something more must be proved to cast liability upon the defendant, though it has been a matter of controversy what additional elements are requisite. I lay stress upon this because observations made by learned judges in actions for rescission have been cited and much relied upon at the bar by counsel for the respondent.
…In my opinion making a false statement through want of care falls far short of, and is a very different thing from, fraud, and the same may be said of a false representation honestly believed though on insufficient grounds. … But the whole current of authorities, with which I have so long detained your Lordships, shows to my mind conclusively that fraud is essential to found an action of deceit, and that it cannot be maintained where the acts proved cannot properly be so termed.