Called in 2019, Sioned Davies practises across the full breadth of planning and environmental law in England and Wales.
Her clients include energy, residential, commercial, minerals, agricultural, infrastructure and logistics developers, statutory undertakers in the water and energy sectors, public bodies (including the Welsh Ministers) and other interested parties.
She appears led and unled at hearings, inquiries, examinations, and in the courts up to the Supreme Court. She is regularly instructed as sole or junior counsel in major multi-week inquiries and examinations relating to the forms of development above. She also has a focus on emerging areas of environmental regulation, including carbon, natural capital and biodiversity.
Sioned is consistently recognised by Planning Magazine as a leading junior under 35, features among its overall top 20 junior barristers and among the leading barristers for specialist commercial planning work. She is ranked as a “Leading Junior” by Legal 500 (London) and as a “Rising Star” (Midlands and Wales). She was awarded BLS Junior Barrister of the Year and was shortlisted for the Legal 500 Planning Junior Barrister of the Year in 2025.
Sioned is appointed to the Welsh Government Panel of Approved Counsel and the Attorney General’s London C Panel.
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. Sioned recently provided the annual legal update to the RTPI Minerals Conference.
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 a particular specialism in the agricultural and rural sector. She has considerable experience advising on agricultural schemes, including renewable energy infrastructure on farms, anaerobic digestion schemes and intensive livestock installations. She regularly advises commercial farming operations on navigating phosphates and nitrates regulation, including on development near protected rivers.
She is very familiar with the complex regulatory landscape for permitting, EIA and Habitats Regulations, and acted in R (Caffyn) v Shropshire Council [AC-2024-CDF-000111] relating to the grant of planning permission for an intensive agricultural installation.
Sioned also advises on novel and emerging agricultural development and on the fast-developing law around natural capital, including biodiversity net gain and nutrient neutrality. As a Nuffield Farming Scholar, she is researching novel regulatory frameworks for insect protein production, and she advises the UK Edible Insect Association.
Date: 21 Sep 2026 - Time: 8:30am - 2:30pm BST
Location: Marriott Bristol Royal Hotel
Earlier this week, No5 Barristers’ Chambers were proud to sponsor the Royal Town Planning Institute’s 2026 Minerals Conference, which took place in central London. The…
"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: 21 Sep 2026 - Time: 8:30am - 2:30pm BST
Location: Marriott Bristol Royal Hotel
Earlier this week, No5 Barristers’ Chambers were proud to sponsor the Royal Town Planning Institute’s 2026 Minerals Conference, which took place in central London. The…
