9 M&W 54 where Parke B said: I think that where money is paid to another under the influence of a mistake, that is, upon the supposition that a specific fact is true, which would entitle the other to the money, but which fact is untrue, and the money would not have been paid if it had been known to the payer that the fact was untrue, an action will lie to recover it back, and it is against conscience to retain it: … If indeed, the money is intentionally paid, without reference to the truth or falsehood of the fact, the plaintiff meaning to all events, whether the fact be true or false, the latter is certainly entitled to retain it; but if it is paid under the impression of the truth of a fact which is untrue, it may, generally speaking, be recovered back, however careless the party paying may have been, in omitting to use due diligence to inquire into the fact…”