The other matter which has required some consideration is this. The case is clearly one of alternative liability. Either Moloney or Pulbrook might be liable to the plaintiff, but both could not be. In such a case a final election to treat either as liable would preclude the plaintiff from proceeding against the other, and it is a well-settled general principle that, while the commencement of an action against one of two persons alternatively liable does not, the entry of judgment against one of them does, constitute a final and irrevocable election: see Morel Bros. & Co. Ltd. v. Earl of Westmoreland [1] . In the present case the plaintiff (as she was clearly entitled to do) proceeded against both of the persons possibly liable, claiming alternatively as against each. After Walker J. had pronounced his decision she entered judgment against Pulbrook. Did this amount to a final election to treat Pulbrook as liable to the exclusion of Moloney? Apart from appeal, clearly it would amount to such an election. But the judgment was subject to appeal, and we do not think that the plaintiffcan, by suing in the alternative and having judgment against one defendant, be precluded from maintaining on appeal that the judgment against that defendant should be discharged and that judgment should go against the other defendant. This is what the plaintiff seeks on this appeal, for her notice of appeal asks that the whole of the judgment of Walker J. should be set aside and that in lieu thereof the judgment should be against Moloney. She has never asked, or put herself in a position where she must be treated as asking, for a judgment against both defendants. Herein the case differs from Morel Bros. & Co. Ltd. v. Earl of Westmoreland [1] and from Moore v. Flanagan [2] . In each of those cases the plaintiff had obtained judgment against one of two defendants, of whom one but not both might have been liable, and then, without setting aside or seeking to set aside that judgment, had sought judgment against the other. This offended against the rule stated by Atkin L.J. (as he then was) in Moore v. Flanagan [3] that "a plaintiff cannot sue an agent to judgment and then sue the principal". The plaintiff in this case is not offending against that rule. It is to be noted that, although the rule is often stated in terms which would seem to make it depend on election, Vaughan Williams J. (as he then was) in Hammond v. Schofield [4] said: - "The basis of this defence is not the election or unconscious election, if there can be such a thing, of the plaintiff, but the right of the co-contractor when sued in a second action on the same contract to insist, though not a party to the first action, on the rule that there shall not be more than one judgment on one entire contract". This passage is quoted by Scrutton L.J. in Moore v. Flanagan [5] . Moore v. Flanagan [2] was not, and this case is not, a case of "co-contractors", but the same rule is applicable, and it must rest on the same basis. There must not be more than one judgment where there is only one antecedent obligation. What Vaughan Williams J. said in Hammond v. Schofield [1] seems to be in accord with what Lord Cairns said in Kendall v. Hamilton [2] . In Buckingham v. Trotter [3] Darley C.J., speaking for the Full Court, said: - "The principle to be deduced from the authorities is that, in the case of principal and agent, the election to sue one or the other is not concluded until after final judgment has been obtained against the one or the other, but, after obtaining this final judgment against the one, so long as it remains of record, no action is maintainable against the other, lest such second action bring about the inconvenient results alluded to by Lord Cairns in Kendall v. Hamilton" [1] . Here the plaintiff asks that judgment against the one shall no longer remain of record but that judgment against the other shall be substituted for it. There is no rule which prevents her from doing this.