Boundary Demarcation Agreements Bind Successors Irrespective of Knowledge

White v Alder & Anor [2025] EWCA Civ 392 (Court of Appeal, Civil Division)

Introduction

White v Alder is a significant Court of Appeal decision that resolves a long‑standing uncertainty in English property law about the legal effect of boundary demarcation agreements on successors in title, and whether knowledge or notice is required for such agreements to bind them. The dispute arose between neighbours in Essex—Mr White (owner of Willow Cottage) and Professor and Mrs Alder (owners of the adjoining property, The Old Stores)—concerning alleged trespass arising from building works and the proper location of the boundary line and ownership of boundary features.

The parties’ predecessors (the Hobsons and the Joneses) had, shortly before selling to Mr White and the Alders in 2005, reached an oral agreement later recorded in writing with a plan demarcating the boundary and attributing ownership of the boundary features (the “Boundary Agreement”). In 2016 and 2019, boundary-related disputes escalated when Mr White demolished part of the wall and commenced construction, prompting the Alders’ claim for damages, injunctions, and declaratory relief.

At first instance, District Judge Mills determined preliminary issues only: the existence, character, and legal effect of the Boundary Agreement. He held that the agreement clarified an uncertain boundary (rather than conveying land) and bound successors in title. HHJ Duddridge, on appeal, upheld that analysis. The Court of Appeal granted permission on a focused point: whether a demarcation boundary agreement binds successors and, if so, whether knowledge or notice is a precondition to being bound.

The Court of Appeal dismissed Mr White’s appeal, holding that a boundary demarcation agreement has proprietary effect and binds successors in title irrespective of their knowledge of the agreement. In doing so, the court reaffirmed and clarified the long‑standing line of authority starting with Neilson v Poole and addressed perceived tensions arising from comments in Gibson v New.

Summary of the Judgment

• The Court re‑endorsed the two‑category framework for boundary agreements:
  • Category 1: An agreement intended to move a boundary by transferring land between neighbours (a conveyancing transaction) that must comply with statutory formalities.
  • Category 2: An agreement intended solely to demarcate an uncertain boundary, even if a trivial transfer of land is a conscious or incidental consequence; such agreements do not require the formalities of a conveyance.
• A Category 2 demarcation agreement is proprietary in nature: it clarifies and fixes the legal boundary as part of the definition of the estates conveyed. It therefore binds successors in title without the need for registration or knowledge/notice.
• The Court rejected the argument that Gibson v New had altered the law. The relevant statements in Gibson about binding successors were obiter and concerned the scope of declaratory relief in that case, not the general legal effect of boundary agreements.
• Knowledge or notice is not required: by defining the parcels, a demarcation agreement determines what a vendor can and does convey. A purchaser cannot acquire more land than the vendor owned; in registered land, although title is conferred by registration (LRA 2002 s 58) and the register ordinarily shows only a general boundary (s 60), a prior demarcation agreement fixes the exact boundary and thus the extent of the registered estate.
• Public policy strongly favours upholding demarcation agreements as “acts of peace” that reduce uncertainty and litigation cost, without undermining conveyancing formalities.

Detailed Analysis

Precedents Cited and Their Influence

• Neilson v Poole (1969) 20 P&CR 909:

  The seminal authority. Megarry J distinguished two types of boundary agreements: (1) those that transfer land and (2) those that merely demarcate unclear boundaries. He held that demarcation agreements are not contracts to convey land, do not require registration as land charges, and bind successors. He emphasised the policy that boundary agreements are “acts of peace” and are to be favoured. The Court of Appeal in White v Alder treats Neilson as the core ratio: a demarcation agreement fixes the boundary and, by defining the estates, binds successors without registration or knowledge.

• Joyce v Rigolli [2004] EWCA Civ 79:

  Arden LJ reaffirmed Neilson, holding that section 2 of the Law of Property (Miscellaneous Provisions) Act 1989 does not apply to pure demarcation agreements, even where trivial transfers are consciously involved. The Court in White v Alder draws on Joyce to emphasise that demarcation agreements are about certainty, not conveyance, and can be effective without writing, consistent with public policy. Though not a successor case, Joyce underpins the doctrinal foundation.

• Haycocks v Neville [2007] EWCA Civ 78:

  Lawrence Collins LJ stated that demarcation agreements bind successors without a written agreement. Although obiter on successors, the dictum is a robust appellate endorsement of Neilson. White v Alder adopts this endorsement and integrates it into a coherent line of authority.

• Nata Lee Ltd v Abid [2014] EWCA Civ 1652:

  Briggs LJ explained the consideration for demarcation agreements as the substitution of certainty for uncertainty, and again distinguished demarcation from conveyance. White v Alder cites and relies on this explanation to show why demarcation agreements are binding between the parties and why, as definitional of the parcels, they bind successors.

• Burns v Morton [2000] 1 WLR 347 (CA) and Stephenson v Johnson [2000] EG 92 (CS) (CA):

  Both Court of Appeal authorities dealing with implied boundary agreements, each treating the agreements as binding in a way that negated the need to decide estoppel. White v Alder notes that while the ratio on the successor point is not crystal‑clear, these cases are consistent with the Neilson line and reinforce that demarcation alone can bind successors.

• Gibson v New [2021] EWHC 1811 (QB):

  Concerned a settlement agreement to accept an expert’s boundary determination and a declaration enforcing that contractual commitment. Murray J’s comments that such an agreement “does not bind successors in title” were made in the context of the declaration’s effect and were obiter dicta. White v Alder explains that Gibson neither revisited nor displaced Neilson. It addressed the scope of declaratory relief and the binding effect between the parties to a settlement agreement, not the general proprietary effect of true boundary demarcation agreements on successors.

• Precedent and ratio/obiter methodology: Kadhim [2001] QB 955; Colchester Estates [1986] Ch 80; R (Youngsam) v Parole Board [2019] EWCA Civ 229; Churchill v Merthyr Tydfil [2024] 3 All ER 771:

  The Court uses these authorities to frame when a proposition forms part of a case’s ratio decidendi and how to treat competing decisions. Leggatt LJ’s refined conception of “necessary” (as part of the best or preferred justification) is invoked to isolate binding reasoning. This methodology supports treating Neilson’s demarcation principle as ratio and Gibson’s successor comments as obiter.

Legal Reasoning

• Two distinct species of boundary agreement:
  • Conveyance-type agreements (moving the line to exchange non-trivial land) require compliance with statutory formalities (LPA 1925; LP(MP)A 1989 s 2; registration if registered land).
  • Demarcation agreements (resolving uncertainty, even if they result in a trivial land adjustment, whether consciously or incidentally) are not “contracts to convey land.” They require no writing, no registration as land charges, and are valid based on consideration consisting of certainty and avoidance of future disputes.
• Proprietary effect without knowledge/notice:

  The Court’s central insight is that a true demarcation agreement does not operate by creating a separate, registrable, equitable interest. Rather, it defines the extent of the estates being conveyed. In unregistered land, the vendor cannot convey more than they own. In registered land, section 58 LRA 2002 confers title on registration, but the registered plan is a general boundary (s 60), so the precise boundary can be established by extrinsic evidence, including a prior demarcation agreement. Once the parcels are defined, successors take the land as defined; knowledge or notice is irrelevant because the effect is not in personam but part of the property’s description.

• No dependence on adverse possession or estoppel:

  Although such factors sometimes coexist in boundary disputes, the Court rejects the notion that successors are bound only where there is “something more” than the agreement. Neilson’s reasoning (and Joyce, Nata Lee) shows that demarcation agreements stand on their own proprietary footing. References to limitation in Neilson were concerned with registration consequences, not the source of binding effect.

• Public policy:

  Demarcation agreements are “acts of peace” that favour certainty, reduce litigation, and avoid disproportionate formalities where only trivial land adjustments are implicated. Requiring knowledge/notice would undercut these benefits and generate uncertainty at each transfer. The policy balance is preserved by the rule that only true conveyancing agreements (i.e., non-trivial transfers intended to move the boundary) must comply with statutory formalities.

• Gibson v New reconciled:

  The Court confines Gibson to its context: a declaration enforcing a settlement agreement between parties does not, by its own force, bind non-parties. That proposition is compatible with the present holding because a true demarcation agreement is not merely a contract; it fixes the boundary and therefore defines the property itself. The Court’s careful application of ratio/obiter methodology ensures that Gibson does not displace the Neilson line.

Impact and Future Significance

• Settled law on successors: This decision firmly reaffirms that boundary demarcation agreements bind successors in title without any knowledge/notice requirement. It closes the door on arguments based on Gibson that might otherwise have destabilised routine, sensible neighbourly adjustments.
• Conveyancing practice:
  • Demarcation agreements should be recorded clearly (ideally in writing with a plan) to aid proof. While not required for validity, documentary clarity reduces later evidential disputes.
  • Sellers should disclose any boundary agreements in pre‑contract enquiries (e.g., TA6) to manage expectations, avoid misrepresentation risks, and facilitate smooth completion even though the agreement binds regardless.
  • For maximum certainty on the register, parties may seek a determined boundary under LRA 2002, s 60 and Land Registration Rules 2003, rr 118–119. Although not a precondition to binding effect, it provides conclusive clarity.
• Dispute resolution:
  • Mediation and expert determination remain valuable tools. However, to create a proprietary demarcation effect binding on successors, the parties should ensure their settlement is framed as a boundary demarcation agreement rather than only a contract to accept an expert’s decision.
  • Judges can grant declarations reflecting a demarcation agreement’s effect; Gibson cautions that declarations simply enforcing a contract between parties do not, by themselves, bind third parties unless the underlying agreement is truly demarcatory.
• Litigation strategy:
  • Parties can rely on historical demarcation agreements (express or implied) without having to prove estoppel or adverse possession, provided the agreement can be proved and is of the demarcation type.
  • Arguments that successors must have knowledge/notice are now foreclosed in demarcation cases.
• Land Registry practice:
  • The case aligns with the general boundary principle: title plans are indicative, and exact boundaries can be established by extrinsic evidence, including boundary agreements.
  • Where parties want the register itself to reflect the exact line, they should consider a determined boundary application; an informal agreement alone is not a registrable interest as such.
• Risk management:
  • Buyers should ask targeted enquiries about any boundary arrangements and review historic correspondence/plans. While absence of knowledge does not prevent the agreement binding, early awareness mitigates the risk of remedial costs.
  • Where an agreement is uncertain, parties should seek to re-document it or agree a determined boundary to avoid evidential disputes.

Complex Concepts Simplified

• Boundary demarcation agreement:

  A neighbourly agreement that fixes an unclear boundary line on the ground, to match what the deeds or plans were always intended to reflect. It does not aim to “sell” land. It is valid even without writing or registration and binds successors because it defines the parcels themselves.

• Agreement to transfer land (conveyance-type):

  An agreement deliberately moving a boundary to exchange non-trivial areas of land. This is a disposition of an interest in land and must comply with statutory formalities (e.g., a written contract signed by both parties) and, for registered land, registration.

• Ratio decidendi vs obiter dicta:

  The ratio is the rule of law treated by the judge as part of the best justification for the outcome. Obiter are comments not necessary for the decision. White v Alder treats Neilson’s demarcation principle as ratio; Gibson’s general comments on successors were obiter in the context of declaratory relief.

• General vs determined boundaries (LRA 2002 s 60):

  Most registered title plans show general boundaries only. A determined boundary is a formal process to fix the exact line on the register. Demarcation agreements can be used as evidence toward a determined boundary but are binding even without it.

• Knowledge/notice:

  Usually relevant for equitable interests or overriding interests. Not relevant here because the demarcation agreement is not a separate interest: it defines the land itself. Therefore, successors are bound even without knowledge.

• Adverse possession and estoppel:

  Separate doctrines that can affect boundary disputes. The Court confirmed a demarcation agreement does not depend on them; it stands alone as a proprietary definition of the boundary.

Practical Guidance and Checklists

For Landowners and Neighbours

• When agreeing a boundary line, make explicit that the purpose is to demarcate an uncertain boundary, not to transfer land.
• Record the agreement in writing with a clear plan (scaled if possible). Identify features (walls, fences, hedges) and who owns them.
• Keep the agreement with the title deeds and disclose it on sale; while not essential to binding effect, transparency avoids later surprises and claims.
• Consider applying for a determined boundary if you want the register to reflect the exact line.

For Conveyancers

• Enquire expressly about any boundary agreements or historic demarcations; seek copies of plans and correspondence.
• Explain to clients that such agreements bind successors regardless of knowledge; factor into advice on extensions, fences, and potential trespass exposure.
• Where parties wish to adjust the boundary by more than a trivial area with an intention to transfer, use a formal transfer complying with LP(MP)A 1989 s 2 and register the disposition.
• Where appropriate, propose a determined boundary application supported by the demarcation agreement and survey evidence.

For Litigators

• Plead the existence and demarcatory nature of the agreement; annex the plan; identify any supportive conduct (e.g., erection of a fence/wall in accord with the agreed line).
• Do not rely on Gibson to argue that successors are not bound or that knowledge is required; White v Alder closes that route.
• Where settlement is reached at mediation, draft the settlement as a boundary demarcation agreement (not merely a contract to accept an expert’s outcome) if proprietary effect is intended.

How the Court Applied the Law to the Facts

The Court accepted findings that the parties’ predecessors reached a demarcation agreement before the sales to Mr White and the Alders. It held that the agreement merely clarified an uncertain boundary and did not amount to a conveyance. On that basis:

• The agreement bound both original parties and their successors as it defined the parcels. It was irrelevant that Mr White said he lacked knowledge at purchase.
• No estoppel or adverse possession was required to render it binding on successors.
• Gibson did not dictate a different outcome; its commentary on binding successors was obiter and focused on the limited effect of a declaration enforcing a contract between the parties.

Key Takeaways

• New/clarified rule: A boundary demarcation agreement has proprietary effect and binds successors in title irrespective of their knowledge or notice.
• Demarcation vs conveyance: Only agreements whose purpose is to transfer land must comply with formalities. Agreements to resolve boundary uncertainty do not.
• Public policy: Courts will uphold demarcation agreements as “acts of peace,” favouring certainty and proportionate cost.
• Proof matters: While writing is not essential, clear documentary evidence and plans ease proof and reduce later dispute costs.
• Registration pathway: Consider a determined boundary if parties want the exact line reflected on the register; otherwise, the agreement still binds without it.

Conclusion

White v Alder decisively settles an area of practical importance in land law. Reaffirming the Neilson line and integrating subsequent appellate endorsements, the Court holds that a true boundary demarcation agreement is proprietary in effect because it defines the land itself. It binds successors in title without any requirement of knowledge or notice. Gibson v New does not stand in the way; its relevant comments were obiter and concerned declaratory relief in a different context.

The judgment provides a coherent and principled framework that protects sensible, low‑cost boundary settlements while preserving the formalities for transactions that genuinely transfer land. It advances certainty in conveyancing and litigation, and it will be the leading modern authority for boundary disputes where demarcation agreements—express or implied—are in play.