Sioned Davies has gained a broad range of experience across planning and environmental law in both England and Wales. Sioned advises a wide range of clients including residential, commercial, energy, minerals and logistics developers, public bodies including the Welsh Ministers, and other interested parties.
She has appeared led and unled in hearings, at inquiries and in the courts. She has appeared in the Magistrates, County Court, High Court, Court of Appeal and Supreme Court. She regularly appears as sole or junior counsel in significant multi-week inquiries, including on residential, renewable energy, commercial or minerals development.
Sioned is recognised as a leading junior under 35 (ranking in 3rd in 2024) by Planning Magazine. She has also been recognised in the overall top 20 junior barristers in this area of law (2023, 2024) and overall, for specialist commercial planning work (2023). She is also ranked as a Leading Junior by Legal 500 (London), and as a “Rising Star” (Midlands Circuit and Wales and Chester Circuit).
Sioned is currently BLS Junior Barrister of the Year and has been shortlisted for the Legal 500 Planning and Land Use Junior Barrister of the Year 2025.
Sioned has worked on several renewable energy matters, including solar, offshore wind and tidal schemes.
Recent instructions include:
Sioned has experience in advising on highways matters. This includes the assessment of evidence and appearing at hearings dealing with specialist highway issues.
Current and recent instructions include:
Sioned regularly advises on the merits of bringing a High Court challenge, and on the defence of such claims.
Recent instructions include:
Sioned also has experience in seeking injunctive relief in the higher courts on her own and led. She was junior counsel in obtaining a “Route Wide” Injunction for trespassers on the HS2 line (junior to Richard Kimblin KC)
Sioned has gained broad experience of infrastructure planning and consenting regimes in both England and Wales.
Throughout her pupillage, she gained experience of challenges to major infrastructure projects, including offshore decommissioning projects in the North of England, to HS2, Drax Power Station, and the North London Heat and Power Project.
Recent instructions include:
Sioned has experience acting for promoters and objectors of mineral and waste projects, both in inquiries and in courts.
Recent experience has included:
Sioned advises on allocations and prospects of bringing forward development through Plans. She is able to assist in making representations at the plan-making stage for all stakeholders. She is familiar with scrutinising the evidence base required to promote or challenge sites in a Local Plan. She is familiar with making representations for developers to examiners of Neighbourhood Plans. She also has experience of legal challenges to plans.
Recent instructions include:
Sioned has considerable experience in representing all stakeholders at planning appeals including both as sole and junior counsel.
This includes acting for a wide range of clients including residential, commercial, energy and minerals developers, public bodies and other interested parties.
This also involves a full range of issues including need (including housing and supply) heritage, landscape, flood risk, highways, ecology, and carbon.
Recent instructions include:
Sioned has experience in planning enforcement. This includes advising on the evidence, investigation and service of enforcement notices and acting for appellants at hearings and inquiries.
Recent instructions include:
Sioned has considerable experience in advising on residential development, both in her own capacity and as part of a team.
Sioned has appeared in a wide range of successful residential appeals including across London, the south east, south west, midlands and Wales, and in areas with particular planning constraints, including in Green Belt and in National Landscapes.
Key issues have included housing land supply/need, heritage, landscape, affordable housing, drop-in permissions, self-build/custom build, ecology, biodiversity net gain, and planning obligations.
In her own right, she has advised several housebuilders and land promoters on different aspects of the development life cycle, including Bloor, St Modwen, R2 Developments, Martin Grant Homes, Manor Oak Homes, BDW, Redrow and Greymoor Homes.
Current and recent instructions include:
Sioned has experience in advising on employment or logistics development. Recent instructions include:
Sioned advises on issues resulting from the introduction of mandatory Biodiversity Net Gain (BNG). She advises developers and public bodies on the practicalities of BNG and as part of a wider natural capital offering.
She is available for talks and training on this rapidly developing area of law.
Sioned regularly advises all stakeholders about risks and opportunities relating to climate change. This includes both mitigation and adaptation.
Her experience has encompassed advising on the generation of policies, EIA, SEA, Whole Life Carbon Assessment (WLCA), renewable energy infrastructure and climate-related legal challenges. She also has experience in advising on flooding issues including the application of the sequential test.
Recent instructions have included:
Prior to coming to the Bar, Sioned was Head of the Secretariat to the Climate Law and Governance Initiative at COP 24 in Katowice, Poland. This event brought together lawyers in the global climate discussion including from states, the World Bank, Green Climate Fund and leading law firms.
Sioned has advised on contentious aspects of environmental assessment (EIA and SEA) for promoters and assessors of various types of development. This has included litigation on matters concerning the adequacy of the EIA.
Sioned has undertaken a number of environmental prosecutions in respect of environmental regulatory matters. This has included an assessment of detailed expert evidence and advice on settlement.
Sioned has appeared in several statutory nuisance matters. This has included prosecuting and defending (concerning individuals, Local Authorities, residential and commercial developers). She is familiar with the assessment of detailed expert evidence including best practicable means and advising on settlement.
Sioned regularly advises on protected habitats and species and the implications for all parties. She has advised developers regularly on how to navigate this regulatory landscape including in respect of phosphates and nitrates issues in England and Wales.
Recent instructions have included:
Sioned has gained considerable experience advising on schemes for all manner of renewable and agricultural installations, ranging from supporting renewable energy infrastructure on farm to anaerobic digestion schemes and intensive livestock installations. She is also a current Nuffield Farming Scholar and is interested in emerging regulatory and policy frameworks concerning agricultural development.
Date: 17 Nov 2025Time: 9:30am - 1pm GMT
Location: No5 Barristers' Chambers
No5’s Planning and Environment group is pleased to announce the appointment of Thea Osmund-Smith and Hugh Richards as our new joint Heads of Group, and…
"Only called to the bar in 2019, Sioned Davies has developed a varied practice since joining No5 Barristers Chambers in the following year. This has included acting in several solar, minerals and residential appeals as sole counsel, as well as advising on such schemes. This expertise includes environmental law issues, like biodiversity net gain and natural capital, where one leading planning solicitor notes that Davies is “clearly on top of the brief”. In addition, the Welsh-born barrister has a “particular expertise” on advising on planning matters in the principality, says a consultant. She describes as “phenomenal” Davies’ ability to take “complex, or quite diverse matters, and distill them into very clear and very distinct advice, particularly for somebody at her level"
"Advocacy at public inquiry is real strength - Sioned displays excellent qualities in terms of her prep, thoroughness, understanding of the case and relevant case law and precedents and communication skills."
Date: 17 Nov 2025Time: 9:30am - 1pm GMT
Location: No5 Barristers' Chambers
No5’s Planning and Environment group is pleased to announce the appointment of Thea Osmund-Smith and Hugh Richards as our new joint Heads of Group, and…
