Single storey infill extension and conversion of garage into annexe accommodation including 1 no. bedroom, lounge kitchen and bathroom

Appeal Decision Site visit made on 8 September 2026 by Lynne Evans BA MA MRTPI MRICS an Inspector appointed by the Secretary of State Decision date: 15 September 2026 Appeal Ref: 6012494 Hole Barn Farm, Brighton Road, Henfield BN5 9SU • The appeal is made under section 78 of the Town and Country Planning Act 1990 (as amended) against a refusal to grant planning permission. • The appeal is made by Mrs Janet Millman against the decision of Horsham District Council. • The application Ref is DC/26/0274. • The development proposed is single storey infill extension and conversion of garage into annexe accommodation including 1 no. bedroom, lounge kitchen and bathroom. Decision 1. The appeal is allowed and planning permission is granted for single storey infill extension and conversion of garage into annexe accommodation including 1 no. bedroom, lounge kitchen and bathroom at Hole Barn Farm, Brighton Road, Henfield BN5 9SU in accordance with the terms of the application, Ref: DC/26/0274, subject to the conditions set out in the schedule at the end of this decision letter. Preliminary Matters 2. A new National Planning Policy Framework (Framework) was issued on 17 August 2026, which replaces the previous Framework published in December 2024 and all other iterations. I have therefore written to seek the views of the Appellant and the Council on the revised Framework as pertinent to this appeal. I have taken the further representations received into account. Main Issue 3. The main issue in this appeal is whether the proposed development would accord with the development plan in terms of the location of new development. Reasons 4. The appeal property is a detached dwelling on a large plot on the east side of a private road leading off the A281, in a countryside location. There are a small number of other dwellings served by the same lane and a scattering of dwellings on both sides of the A281 with open countryside between. 5. The proposal relates to conjoining two existing outbuildings close to the existing house with a modest new addition to create a self-contained annexe for the existing resident of the main house, with her family moving into the main house. The proposed annexe would contain full facilities including a kitchen and dining area, as well as snug and one bedroom with bathroom facilities. Appeal Decision 6012494 2 6. The planning application was submitted on the basis of it being an annexe to the main dwelling. The Council accepted the householder application on this basis and the decision notice specifically refers to annexe accommodation. 7. Policy 28 of the Horsham District Planning Framework (2015) (DPF) relates to replacement dwellings and house extensions in the countryside, including ancillary accommodation, and states that such development will be supported if the development can be accommodated appropriately within the curtilage of the existing dwelling. Specific further guidance under the policy states that ancillary accommodation should meet all other appropriate policies and demonstrate the need for additional space cannot be met from an existing dwelling or buildings suitable for conversion on the site. The size of the outbuilding should have regard to the dwelling they serve and should be grouped with the house. The use of ancillary accommodation as a separate dwelling will not be supported. 8. There would be no proposed subdivision of the planning unit, and the proposed development would be wholly within the curtilage of the existing dwelling, utilising two existing outbuildings, which would be connected through a modest new extension. The proposed annexe would be modest in size and scale in relation to the main dwelling on the site. The new link would also be moderate in size and scale and appropriately designed to maintain the appearance of the two existing outbuildings. The siting of the existing outbuildings are close to the main house and would continue to be seen as smaller scale outbuildings within the curtilage of the main house. 9. The Council’s sole reason for refusal relates to the principle of the proposal in terms of it being considered to be tantamount to the creation of a new dwelling. The Officer’s report referenced a number of detailed concerns with the layout, scale and design, albeit primarily in terms of their concern about the proposed development being akin to a new dwelling, most of which I have addressed above. I consider that the conversion of the two existing buildings and moderate sized link extension between would be of a high standard of design and would continue to respect the relationship with the main dwelling. 10. Even if the development could be used as a separate dwelling, there is no separate dwelling before me. In any case, if the proposed building were not used as proposed, or if there were a material change of use in the future to create a separate dwelling, then a separate grant of planning permission would be required. 11. I am therefore satisfied that the proposed development would be acceptable for its submitted use and function, as well as in design terms, as an annexe to the main dwelling at Hole Barn Farm. It would accord with Policy 28 of the DPF as set out above and would not conflict with Policies 2, 3 and 26 of the DPF as well as Policy DP3 and Policy S5:1 of the Framework relating to seek high quality design which respects its context and appropriate forms of development in the countryside and protecting and enhancing the countryside. Other Considerations 12. I am advised that Hole Farmhouse, to the south of the appeal property, is Grade II listed. When considering whether to grant permission for development which affects a listed building or its setting, I am required under Section 66 (1) of The Planning (Listed Buildings and Conservation Areas) Act 1990 to have special Appeal Decision 6012494 3 regard to the desirability of preserving the building or its setting or any features of special architectural or historic interest it possesses. 13. Given the distance between the proposal and the Grade II listed building and the intervening countryside and trees, I am satisfied that there would be no harm to the setting of the listed building; its setting would be preserved. The Council also raised no concerns in this regard. 14. With regard to water neutrality, the Council has undertaken an Appropriate Assessment which demonstrates that the anticipated increase in mains water consumption from this development, alongside all other developments granted since 31 October 2025, would not exceed 3,240,000 litres per day. This is an interim measure agreed between the Council and Natural England to use the significant water savings made by Southern Water in 2024/2025 through their programme of leakage reduction (amongst other measures) and Natural England’s standing advice from November 2025 raises no objection to using these savings to allow new development to come forward. The Council confirms that the standing advice clarifies that it functions as Natural England’s formal response pursuant to Regulation 63(3) of the Conservation of Habitats and Species Regulations 2017 to all relevant planning applications which seek to achieve water neutrality using the above Southern Water savings. 15. As a result, the Council has concluded that the proposed development would not have an Adverse Effect on the Integrity of the Arun Valley site, either alone or in combination with other plans and projects, thereby complying with Regulations 63 and 70 of the Conservation of Habitats and Species Regulations 2017, Policy 31 of the DPF and Policy N6 of the Framework. I have no reason to reach a different conclusion. Conditions 16. Conditions are required to ensure that the materials accord with the details set out on the application forms in order to respect the character and appearance of the existing property and of the local area. The approved plans require to be listed for the avoidance of doubt and in the interests of good planning. 17. Notwithstanding the fact that the sub-division of the planning unit and use of the annexe as a separate dwelling would constitute a material change of use requiring planning permission, I consider that a condition to control the use of the accommodation to be reasonable and necessary to provide clarity about the development applied for and to ensure compliance with Policy 26 of the DPF. Conclusion 18. For the reasons given above and having regard to all other matters raised, I conclude that the appeal should be allowed. L J Evans INSPECTOR Appeal Decision 6012494 4 Schedule of Conditions 1) The development hereby permitted shall begin not later than 3 years from the date of this decision. 2) The development hereby permitted shall be carried out in accordance with the following approved plans: 01, 02, 03 and 04. 3) The external surfaces of the development hereby permitted shall be constructed in the materials set out on the application forms. 4) The annexe as shown on the approved plans shall not be occupied at any time other than for purposes ancillary to the residential use of the dwelling known as Hole Barn Farm, Brighton Road, Henfield, BN5 9SU. End of Schedule