Intervention. A third person not originally a party to a suit, but claiming an interest in the matter, may interpose at any stage of the suit in defence of his own interest, whenever affected either as to person or property. This is called intervention, and was peculiar to the Ecclesiastical and Admiralty Courts. It is now practised in actions or suits in the Probate, Divorce, and Admiralty Division of the High Court. An intervener must take the cause as he finds it at the time of his intervention, and can only do what he might have done had he been a party in the first instance; but the Court may relax this rule under special circumstances.
In probate actions, any person not named in the writ may intervene and appear in the action as heretofore on filing an affidavit showing that he is interested in the estate of the deceased [(English) R.S.C., Ord. XII., r. 23]. And in an Admiralty action it rem any person not named in the writ may intervene and appear as heretofore on filing an affidavit showing that he is interested in the res under arrest, or in the fund in the registry (ibid., r. 24). As to actions for the recovery of land, see ibid., r. 25.
By the (English) Judicature Act, 1925, s. 181, the king's proctor, or any other person, may intervene in any suit for the dissolution of marriage, on the ground that the parties have been guilty of collusion, or that material facts have been suppressed.