Kathleen Donnelly KC
"Kathleen is absolutely stellar."
Chambers UK 2025
- Call
- 2005
- Silk
- 2023
Kathleen has a wide-ranging commercial practice with particular expertise in group actions, product liability, environmental claims, and employment litigation. She is known for her meticulous preparation, strategic thinking, and powerful advocacy—attributes consistently recognised by the legal directories.
Kathleen has acted in some of the most significant class actions before the English courts. She represented the 555 subpostmasters in their civil claim against the Post Office relating to the Horizon IT system. The litigation exposed systemic flaws in the Post Office’s approach and led to the quashing of 93 wrongful convictions—described as the largest miscarriage of justice in UK legal history.
Kathleen acted in the high-profile VW NOx emissions litigation and continues to be instructed in environmental and large-scale group litigation. She has experience in major environmental claims, including the OCENSA pipeline case (which culminated in a five-month trial), private nuisance disputes, and occupational disease claims. She also acted for a key party in the Potters Bar inquest.
Her commercial litigation practice includes acting in the complex and high-value aviation dispute between Qatar Airways and Airbus, as well as the Stirling Mortimer litigation involving fraud and professional negligence claims.
In the employment sphere, Kathleen acts for NEXT in a high-profile equal pay claim which is the first of its kind in the private sector. She is regularly instructed in employee competition disputes and has acted extensively for international civil servants against the African Development Bank. Kathleen also has experience in multi-party arbitration, including in the financial technology sector.
She has particular expertise in cases involving complex technical evidence and expert witnesses. She is frequently instructed in litigation requiring detailed engagement with expert disciplines, and is recognised for her skill in managing and cross-examining expert evidence across scientific, engineering, medical, and financial fields.
Kathleen is consistently ranked by Chambers & Partners and The Legal 500 across multiple practice areas. She is described as “absolutely stellar,” “hugely impressive,” “a real strategist,” and “frighteningly intelligent.” She is commended for her “exceptional cross-examination,” clarity, commerciality, and deep understanding of detail in complex cases. Clients and peers praise her courtroom presence, tenacity, and team spirit, describing her as “a stand-out barrister,” “an expert in environmental law and group litigation,” and “the engine room of the case.”
She studied Law at Oriel College, Oxford, and holds a postgraduate law degree from Queens’ College, Cambridge.
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Expertise
Group Actions
Kathleen has acted in some of the largest and most significant group actions before the English courts, with a particular focus on complex, expert-heavy litigation. Her experience spans commercial, environmental, and employment-related mass claims, often involving multiple parties and extensive technical evidence.
She is adept at managing strategic litigation across multiple workstreams and leading large legal teams. Her cases frequently involve co-ordination between claimant groups, expert teams, and international stakeholders. She is regularly instructed in group actions requiring a combination of technical mastery, rigorous advocacy, and tactical foresight.
Representative cases
grid list-
Post Office Group Litigation
Acted for 555 subpostmasters in their civil claim against the Post Office concerning the defective Horizon IT system. The case led to the exposure of the UK’s most serious miscarriage of justice, with 93 wrongful convictions overturned following the High Court’s findings on the unreliability of the system.
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VW NOx Emissions Group Litigation
Acted for VW in this long-running and high-profile group action (2015–2021) arising from emissions control systems in diesel vehicles. Kathleen continues to be instructed in the second wave of diesel emissions litigation brought against a broad range of manufacturers across the industry.
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Equal Pay Group Litigation
Acting for NEXT in a high-profile equal pay claim brought by more than 2,000 employees. The litigation raises novel and complex issues in the private sector context and is the first of its kind in that field.
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OCENSA Pipeline Group Litigation
Acted in a major environmental action arising out of alleged contamination and damage caused by an oil pipeline in Colombia. The case concluded in a five-month High Court trial and involved extensive technical and expert evidence.
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Sports Direct Bonus Group Litigation
Acting for Sports Direct in a group action brought by part-time employees relating to bonus payments and contractual entitlements.
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Arkwright In Vessel Composting Site Group Litigation
Instructed in a group private nuisance claim concerning alleged odour nuisance arising from a composting facility.
Product Liability
Kathleen has significant experience in product liability disputes, particularly in complex multi-party litigation involving safety-critical products and technical failings. Her practice spans the manufacturing, transport, energy, and healthcare sectors, often in cases involving extensive expert evidence and international dimensions.
She is regularly instructed in high-value product liability claims where issues of engineering, compliance, and causation are central, and has acted both for claimants and major corporate defendants. Her work includes some of the most prominent product liability litigation in recent years.
Representative cases
grid list-
Qatar Airways v Airbus
Acting for Qatar Airways in this high-profile commercial and product liability dispute concerning surface degradation and the grounding of the A350 aircraft. The case involves complex technical, regulatory, and contractual issues relating to aviation safety and airworthiness.
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VW NOx Emissions Litigation
Acted for VW in this long-running product liability group action (2015–2021) concerning emissions control systems in diesel vehicles. Kathleen continues to be instructed in further litigation involving allegations against manufacturers across the diesel industry.
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OCENSA Pipeline Litigation
Acted in large-scale litigation concerning alleged environmental damage arising from the construction and operation of an oil pipeline in Colombia. The case involved engineering evidence on design and materials and concluded in a five-month trial.
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Forklift Truck Emissions Compliance Proceedings
Instructed in litigation concerning compliance failures in diesel-powered forklift trucks, raising issues of regulatory breach and engineering defect.
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Surgical Navigation System Inquest
Appeared in an inquest concerning the death of a patient during cranial surgery involving a surgical navigation system, raising issues of medical device reliability and product performance.
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Playground Equipment Claim
Acted in a claim involving alleged design and manufacturing defects in playground equipment leading to injury.
Environment
Kathleen has extensive experience in large-scale environmental litigation, including group actions and high-profile civil proceedings. Her work spans waste management, emissions, mining, and the rail industry. She is regularly instructed in cases where environmental impact is in issue, including nuisance claims and complex disputes involving technical operational systems.
She has particular expertise in working with expert evidence in environmental science, engineering, and occupational health, and is known for her ability to handle complex, technical subject matter with clarity and precision.
Representative cases
grid list-
VW NOx Emissions Group Litigation
Acted for VW in this major group action (2015–2021) concerning vehicle emissions and compliance with environmental standards. Kathleen continues to be instructed in further emissions litigation involving a range of automotive manufacturers.
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Arkwright In Vessel Composting Site Group Litigation
Instructed in a private nuisance group claim relating to odour emissions from a composting facility, involving regulatory, operational, and permitting issues.
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OCENSA Pipeline Group Litigation
Acted in large-scale litigation concerning allegations of environmental damage linked to the construction and operation of an oil pipeline in Colombia. The case concluded in a five-month High Court trial and involved complex expert evidence.
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Powertrain Group Litigation
Instructed in a group claim concerning alleged respiratory conditions said to result from exposure to metalworking fluids in an industrial setting.
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HSE v UK Coal, Alstead and Davison
Acted in criminal proceedings brought by the Health and Safety Executive following a fatal accident at Daw Mill Colliery. The case involved complex regulatory and operational issues in the mining sector.
Employment
Kathleen has a substantial employment law practice, with particular expertise in complex and high-value disputes involving equal pay, employee competition, whistleblowing, and discrimination. Her experience spans the Employment Tribunal, High Court, Employment Appeal Tribunal, and employment-related arbitration, including in the financial technology sector.
She is currently acting for NEXT in an equal pay claim brought by more than 2,000 employees—the first of its kind in the private sector. Her practice includes both individual and group claims, and she is regularly instructed in high-profile and strategically sensitive employment disputes for employers, senior executives, and international civil servants.
Representative cases
grid list-
Equal Pay Group Litigation
Acting for NEXT in a large-scale equal pay claim brought by more than 2,000 employees. The case raises significant legal issues for the retail sector and is one of a number of such claims being pursued against major private sector employers.
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Fintech Arbitration
Acting for an employee in a multi-party arbitration arising out of an employment dispute in the financial technology sector, involving allegations concerning misuse of confidential information and trade secrets.
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Advising CEO of UK Fashion Brand
Advised a chief executive in claims for whistleblowing and sex discrimination brought against a major fashion retailer.
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Advising CEO of UK PR Brand
Advised a senior executive in claims for bonus and sex discrimination involving contractual and statutory elements.
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Jerroms v Tilson
Acted in an employee competition and economic tort claim involving alleged breaches of restrictive covenants and fiduciary duties.
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Aron v African Development Bank
Acted for the claimant in proceedings concerning alleged unlawful termination on grounds of abandonment of post.
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Michelitsch v African Development Bank
Represented the former Evaluator General of the African Development Bank in proceedings concerning termination of employment and institutional fairness.
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Autoclenz v Belcher
Acted in the Court of Appeal in this leading case on worker status and sham contracts.
Arbitration
Kathleen has experience in complex arbitration proceedings involving multiple parties, requiring careful procedural management, detailed engagement with expert evidence, and coordination with parallel High Court litigation. Kathleen is well placed to advise in arbitrations where sensitive commercial issues, technical material, and confidentiality concerns are in play.
Representative cases
grid list-
Fintech Arbitration
Acted in an arbitration under the LCIA Rules seated in London, arising from an employment dispute in the financial technology sector. The case involved allegations of misuse of confidential information and trade secrets, and featured multiple procedural hearings, complex expert evidence, and related High Court proceedings.
What the directories say
"Kathleen's cross-examination is beyond exceptional."
Chambers UK 2025
"Kathleen is fantastic."
Chambers UK 2025
"I think she's great and hugely impressive."
Chambers UK 2025
"She is wonderfully articulate, clear, concise and commercial."
Chambers UK 2025
"I've found her to be user-friendly and a great team player."
Chambers UK 2025
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Instructing Kathleen Donnelly KC
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- King’s Counsel (2023)
- Commercial Bar Association
- Employment Lawyers Association
- Personal Injuries Bar Association
- LLM Commercial and International Law (Cantab) (2003)
- BA (Hons) Jurisprudence (Oxon) (2001)
- Hardwicke Award, Lincolns Inn
- Buchanan Scholar, Lincoln’s Inn
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Legal Status: King’s Counsel
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Regulated by the Bar Standards Board.
