Undertakings in financial remedy orders are commonplace but the recent case of Birch v Birch  EWCA Civ 833 explored the issue of the court’s jurisdiction to vary undertakings on application.
The facts were fairly simple. The Wife obtained a transfer of the family home and gave undertakings to the court to use her best endeavours to secure the Husband’s release from the mortgage covenants by a certain date with a default sale provision. The Wife was unable to comply with the undertaking and sought a variation of the undertaking to enable her to postpone sale until a child of the family had attained their majority. The case was dismissed at first instance by the District Judge and on appeal by the Circuit Judge. The Wife appealed to the Court of Appeal.
The Husband opposed the application on the basis of lack of jurisdiction and relied on the decision of the Court of Appeal in Omielan v Omielan  2 FLR 306. In this case, (Thorpe LJ giving the lead judgment) the Wife’s application to vary one of the trigger events in a ‘Mesher’ order was dismissed on the basis of want of jurisdiction.
In the course of the leading judgment (in Omielan) Thorpe LJ stated:
…s.31(2)(f) gives the court jurisdiction to revisit the territory of the ancillary order under s.24A but not the territory of the primary order under s.24 which it supports. Applying that principle to this case, manifestly the application of 20 January 1995 seeks to revisit the territory of the primary order under s.24. Mr Spon-Smith’s submission that the application seeks only to extend the date of implementation of sale is erroneous. Properly analysed, the wife’s election to cohabit with Mr O’Hagan for more than 6 months in and after 1992 had the effect in law of determining her beneficial interest in possession and of bringing from reversion into possession the beneficial interests of herself and the children in the proceeds for future sale. The application of 20 January 1995 seeks to reverse the termination of a beneficial interest in possession to the detriment of the holders of vested beneficial interests in reversion. These vested beneficial interests in possession and in reversion are that the very core of the s.24 order since they were the interests created to replace the pre-existing joint beneficial ownership of the husband and the wife. Both statute and authority show that the court has no jurisdiction to entertain an application to vary such an order. For those reasons I would allow the appeal and dismiss the wife’s application of 20 January 1995 for want of jurisdiction.
In Birch the court considered that there was jurisdiction to vary under Section 31 of the Matrimonial Causes Act 1973 but stated that this power would be rarely used. They also indicated that the Wife was unlikely to succeed on the merits as it would undermine the basis upon which the order was made.
In the leading judgment, McCombe LJ, explained why the Court were able to distinguish Omielan:
26. It is clear to me that, for many years, in the exercise of their jurisdiction in divorce, the courts have been astute to achieve finality in determining the financial (and in particular the capital) claims of the parties to a marriage. As Thorpe LJ said in Omielan , when capital adjustments have been incorporated in a final order, whether or not by consent, the court has no jurisdiction to “revisit the territory” of those adjustments, in the absence of a vitiating factor such as fraud, misrepresentation or material non-disclosure. He describes it as a “cardinal principle” emerging from cases such as Dinch v Dinch (supra), to which might be added De Lasala v De Lasala  AC 546 and Barder v Calouri  AC 20.
27. To these considerations, as Thorpe LJ also remarked, we must have regard to the statutory context, which makes it clear that a primary property adjustment order under section 24(1)(a) and a lump sum order under section 23(1)(c) are not subject to the section 31 jurisdiction, save (in respect of the latter) a lump sum payable by instalments: section 31(2)(d). The principal function of section 31 is to permit variations of periodical payments and the like. It is also clear, as explained in Omielan , that section 24A is a purely procedural section limited to matters of enforcement, implementation and procedure in respect of any order to which a section 24A order for sale is attached.
28. My view is that the undertakings in this case do not aid the enforcement, implementation or procedure of the primary order for the transfer of the property to the Wife in any respect. The property transfer order, as a matter of construction, enforcement and implementation, is independent of and separate from the undertaking for ultimate sale. The transfer order could be enforced and implemented (even if, as a matter of practicality, the transfer would have to be subject to the mortgage) without recourse to the undertakings which would remain live whether the section 24 order had been implemented or not.
29. It was not argued before us that the court in this case could not/should not have made an order for sale under section 24A in such circumstances as an adjunct to or fall back from the provision in paragraph 4.3. However, it is clear to me that the 1973 Act contains no power that would have made it possible for the court to make any order, analogous to the paragraph 4.3 undertaking, requiring as it does a party to endeavour to secure the release of the other party from mortgage covenants and to indemnify him from liability under them. Accordingly I do not consider that an order under section 24A could have been made in this case in terms of the undertaking in paragraph 4.4 following a failure to comply with the undertaking in paragraph 4.3.
30. Of course, even if there was no such power, it is a recognised process of consent orders of this type to make arrangements, by way of undertakings by one or more of the parties, for matters outside the powers of the court under the 1973 Act. Such undertakings are “enforceable as effectively as direct orders”: see per Lord Brandon of Oakbrook in Livesey v Jenkins  AC 424 at 444F-H. The undertakings are an essential part of the bricks and mortar with which the edifice of such financial orders are constructed.
31. It was, therefore, undoubtedly within the power of the court to extract and/or accept such undertakings as these, without which the order for property transfer would not be made. In the present case, it is clear beyond peradventure that this property order in favour of the Wife would not have been made absent the undertakings now in issue. It is not suggested that an order in a form incorporating the proposed variation was a realistic possibility when the parties were before the court for the final hearing, during the course of which the essential terms of the consent order were negotiated.
32. In the end, applying these considerations and the court’s decision in Omielan (which, while binding upon us, is obviously, however, distinguishable on its facts) the question for me was whether this proposed variation was the equivalent of a section 24A order at all. If it was, did it revisit the “territory” of post-divorce capital adjustments incorporated in a final order, and the “territory” of the final order under section 24 (so as to fall outside the jurisdiction under section 31), or was it merely in the “territory” of an ancillary order under section 24A. If it was not the equivalent of an order under section 24A, would there be jurisdiction, which might sensibly be exercised, to vary this undertaking as now sought.
33. As already indicated, in my judgment, this is not a case involving an ancillary order under section 24A of the Act at all. Indeed, as a matter of form, the undertakings are not such orders, although it was convenient for Mr Hockman is his attractive, but perhaps deceptively simple, argument so to submit.
34. I do not accept, as I have said, that these undertakings are to be regarded as merely incorporating by way of undertaking something that the court would or could have ordered under section 24A. Clearly, paragraph 4.3 could not have been so ordered, with paragraph 4.4 as the fall back if the Wife could not achieve the objective of paragraph 4.3. In my judgment, the undertaking in paragraph 4.4 is not, therefore, an undertaking equivalent to a section 24A order.
35. I consider, therefore, that in truth the Wife’s submission before the judges in the court below was correct on this point. The application before them was an application simply to vary an undertaking contained in a final order
The Wife’s success in the jurisdictional argument was offset by the analysis of the merits of her application to vary the undertaking. McCombe LJ stating as follows:
44. On the basis that I have sought to explain, it seems to me that there does exist a formal jurisdiction in the court to vary this undertaking. However, when the variation sought is, in effect, an attempt to substitute an entirely different outcome from that provided for by the original consent order, the scope for the exercise of the jurisdiction must be extremely limited indeed. While I recognise the existence of the jurisdiction to vary the undertaking, on what we have been told as to the basis of the proposed variation application, I can see no basis upon which the court would exercise the jurisdiction in the present case. In the circumstances, I consider that we should invite further submissions in writing from counsel as to whether the realities dictate that the right course is to dismiss the appeal.
Thus, the principle of achieving finality of litigation continues to provide a powerful obstacle to varying final financial orders. Practitioners will need to ensure that the lay clients are fully aware that any undertakings entered into are likely to be enforced without exceptional Barder counter arguments being present.