Boundary-to-Boundary and Beyond: Inspector’s reasoning upheld in byway width challenge

In Wilkins v Secretary of State for Environment, Food, and Rural Affairs [2025] EWHC 2435 (Admin), the High Court dismissed a challenge to an inspector's decision to confirm a Definitive Map Modification Order. The Kent County Council (Restricted Byway AB27 at Tenterden) Definitive Map Modification Order 2021 ("the Order") recorded the width of Restricted Byway AB27 (RB/AB27), and amended the description to record its width as depicted in the Order plan and described in the Order schedule. 

 RB/AB27 was recorded on the first definitive map as a Road used as a Public Path, and later reclassified as a restricted byway by certain provisions of the Countryside and Rights of Way Act 2000. In 2015, the Claimants instructed a Rights of Way Consultant, Mr Carr, to produce a detailed report investigating its history.  The Claimants then made a series of applications for modifications to the Definitive Map relating to the byway, one of which sought to add widths to the definitive statement. Kent County Council had determined that the width of the route should be scaled off the Ordinance Survey Maps (“OS Maps”). The Claimants objected to that decision, which was upheld by the Secretary of State, with the Inspector holding that it was “appropriate and necessary in the circumstances to define the width of the Order route with reference to the 25 Inch Third Edition OS Map” on the basis that the details within are reliable and the Courts have confirmed the accuracy of the OS maps generally. 

 The Claimants challenged that decision on three grounds, relying on a witness statement from Mr Carr. The Defendant resisted the challenge in its entirety and contended that the witness evidence of Mr Carr was inadmissible in part on the basis that it was expert opinion and did not comply with the requirements of Part 35 of the Civil Procedure Rules relating to Experts and Assessors. 

 Court’s findings

 The High Court considered the following grounds and dismissed the Claimant’s challenge.

•  Ground 1 - Misdirection in Law - that the Inspector had misdirected himself as to the correct legal test in relation to the application of the boundary-to-boundary principle and had failed to have regard to guidance on determining the width of the byway: The High Court held that the Inspector had not misdirected himself as to the boundary-to-boundary principle. The Inspector's task was to see whether the width of the byway recorded should be modified having regard to the available evidence and applying legal principles. In reaching a decision, the Inspector had applied the test for dedication and had found evidence of actual use by the public across the whole width between the relevant boundary features.
• Ground 2 - Departure from previous findings - that the Inspector had unlawfully departed from a previous inspector’s decision without evidence: The Claimant referred to the judgment in R (Sears Group Properties Ltd) v Cardiff CC [1998] PLCR 262. This established that where a decision has been made by a competent authority on a particular issue affecting private rights, that decision will be binding on other authorities unless and until circumstances change in a way that undermines the basis of the original decision. The Claimant contended that the second inspector had unlawfully departed from the decision of a previous inspector. The High Court disagreed and held that the previous inspector’s decision was not binding and was directed at a different question and different issues. As a result, there was no inconsistency.
• Ground 3 – Irrationality - that reliance upon the OS Maps was irrational: The Claimants contended that the scaling off approach produced absurd results and could not be used by any reasonable inspector. However, the Inspector had acknowledged the potential issues with the accuracy of the OS mapping but had concluded that the OS Maps would be significantly more accurate than alleged by the Claimants, as the physical layout of the byway had not changed significantly between the date of the Tithe Map (1843) and the 3rd Edition OS Map.  The High Court held that the inspector was entitled to rely upon the excellent reputation of the OS and to conclude that the Maps represented the best evidence as to the width of the route such that scaling from them was appropriate. 
• Admissibility of Carr's Witness Statement: The High Court held that large portions of Mr Carr’s evidence, to which the Secretary of State had objected, were argumentative and crossed the line into inadmissible expert opinion. They were not before the Inspector and fell to be excluded.

Comment

This case is a useful reminder of a number of points: 

• Applications for modifications to the definitive map can often be contentious and it is important to ensure that the legal test is met and that robust supporting  evidence is provided;
• Whether an earlier decision is relevant to a new finding is highly dependent on the facts of both cases. If inconsistencies arise, then earlier decisions may be distinguished;
• Those providing expert evidence should ensure that Part 35 of the CPR or any other applicable guidance should be followed. 

We have extensive experience in advising on highways matters including modification orders so please get in touch if you have any queries on the case or more generally.