Niamh specialises in professional liability matters, with particular experience in claims against lawyers, valuers, insurance professionals and financial professionals. In addition, Niamh is regularly instructed to advise on policy coverage, contractual disputes and general commercial matters. Her expertise has been recognised by both the Chambers & Partners and Legal 500 directories for many years.
Niamh is a confident and very experienced advocate, and especially enjoys cross-examination. She recently represented the successful respondents in the Court of Appeal case of Guo v Kinder & others [2024] EWCA Civ 762, which concerned the date of issue of a claim form in professional negligence proceedings in circumstances where an earlier unsuccessful attempt to issue had been made.
She also represented the successful solicitor defendants in the recent High Court case of Playfair v Pannells LLP & Shakespeare Martineau LLP and others [2024] EWHC 1933 (Ch), where an application to extend time for service of a multimillion-pound claim was refused.
She is currently instructed on multiple high-value High Court claims, in her own right and as junior counsel to William Flenley KC.
Niamh has acted in litigation against all manner of non-clinical professionals, to include professions as eclectic as funeral undertaking and bovine nutrition. However, she has particular experience of claims against lawyers, surveyors/valuers, insurance professionals and financial professionals.
Lawyers
Niamh has very substantial experience in the field of solicitors’ and barristers’ negligence. She accordingly has specialist knowledge on issues including limitation (with a special interest in section 14A and section 32 of the Limitation Act), causation, duty of care, quantification of damages including loss of a chance and claims for contribution from third parties. She has acted in disputes involving allegations of negligence, breach of fiduciary duty and breach of trust against lawyers in virtually every conceivable area of legal practice. She has a special interest in claims relating to negligence in the preparation of wills.
Surveyors & valuers
Niamh is frequently instructed in claims against surveyors/valuers and is currently instructed in several claims by lenders alleging overvaluation of property portfolios.
Financial professionals
Niamh is regularly instructed in claims against IFAs, and is currently involved in several cases involving allegations of unsuitable investment advice and mismanagement of investments.
Insurance professionals
Niamh has significant experience of acting for insurance brokers. She is currently defending a high-value claim by a major underwriter against insurance coverholders (with William Flenley KC): Amtrust v MD Insurance Services Ltd [2025] EWHC 1468 (Comm).
Niamh is regularly instructed to advise on matters of policy coverage and contractual disputes. She has also acted in High Court and Court of Appeal proceedings under sections 67 and 72 of the Arbitration Act 1996 (with Vernon Flynn KC).
Niamh is very experienced in professional disciplinary proceedings, having represented over 100 nurses before the Nursing and Midwifery Council in respect of all manner of allegations. Her focus is now on the defence of solicitors before the Solicitors Disciplinary Tribunal, work which she particularly enjoys.
Amtrust v MD Insurance Services Ltd [2025] EWHC 1468 (Comm) (ongoing dispute alleging negligence against insurance coverholders; successfully resisted application for swingeing amendments to the particulars of claim by the claimant and summary judgment application by co-defendant) (with William Flenley KC)
Guo v Kinder & others [2024] EWCA Civ 762 (successful defence of appeal to the Court of Appeal on question of date of issue of claim form)
Playfair v Pannells LLP & Shakespeare Martineau LLP and others [2024] EWHC 1933 (Ch) (successful defence of application to extend time for service of a multimillion-pound claim)
Re Sherlock Holmes International Society [2016] EWHC 1392 (Ch); [2016] 4 W.L.R. 173; [2016] P.N.L.R. 31 (successful defence of solicitors in claim for breach of warranty of authority)
Turner v Bromets Jackson Heath LLP [2016] (Leeds County Court, HHJ Behrens) (successful defence of solicitors accused of negligence in respect of a declaration of trust between co-habitees)
Harding Homes v Bircham Dyson Bell [2015] EWHC 3329 (Ch) (ten-day trial resulting in successful defence of solicitors despite admitted breach of duty (with William Flenley KC))
"Niamh O'Reilly is very thorough and easy to deal with. She's generous with her time and works in a collegiate manner with solicitors." Chambers UK, 2026
"Niamh O'Reilly is always highly knowledgeable and professional. In addition, she is great at explaining liability risks to insured clients, who may not always be keen to accept the risks." Chambers UK, 2026
"Niamh O'Reilly has extraordinary vision for a case's strategy and overall management, and this shows when it comes to her advocacy and legal submission. A must-have for professional liability work." Chambers UK, 2026
"Niamh O'Reilly receives superb reviews from her clients describing her as a barrister with experience and authority beyond her years." Chambers UK, 2026
"She is responsive, bright and commercial. An impressive advocate." Legal 500, 2026
"Niamh O'Reilly is hugely bright and an excellent barrister. She is engaging and very strong in court and on paper, particularly with the detail. A very pleasant person to work with." Chambers UK, 2025
"Niamh has very good technical knowledge and commercial awareness." Chambers UK, 2025
"Niamh's technical and procedural knowledge is fantastic. Her advocacy at trial is extraordinary, second to none." Chambers UK, 2025
"Niamh is phenomenally bright and well able to deal with the most complex cases. She is enjoyable to work with too." Legal 500, 2025
"Niamh is a great advocate and equally at home in court or providing written advice." Chambers UK, 2024
"Niamh is excellent and very user-friendly." Chambers UK, 2024
"She is utterly brilliant and the best and most user-friendly barrister I know for professional negligence cases." Chambers UK, 2024
"Very approachable and easy to work with and good technically." Chambers UK, 2024
"She is my go-to barrister on complex professional negligence claims. She is a very impressive person and this shines through in her work." Chambers UK, 2024
"Niamh is always a delight to work with. She is very thorough in her preparation and an exceptional advocate." Legal 500, 2024
"Niamh is a delight to work with. She combines her sharp intellect with a lovely manner, putting even the most nervous clients at ease." Chambers UK, 2023
"Niamh is the first name on the list of recommendations whenever clients or colleagues need a barrister for the most complex or 'nasty' cases." Chambers UK, 2023
"Niamh has a wealth of experience and knowledge, and always impresses me." Chambers UK, 2023
"Really personable, lovely to deal with, bright, commercial and clear." Legal 500, 2023
"Niamh is a very bright and articulate barrister. She has sound commercial judgment and is an impressive advocate." Legal 500, 2023
“She’s brilliant, my go-to for higher-value solicitor negligence cases below the silk level.” Chambers UK, 2022
“She’s an exceptionally good barrister, she gets the judge on side – just incredibly good, a real rising star.” Chambers UK, 2022
“Extremely hard-working, gets into the detail, and very supportive to solicitors on the black-letter advice but also the whole perspective. She is able to give very authoritative advice in very complex areas.” Chambers UK, 2022
“Niamh combines extreme intelligence and an approachable personality. She excels in explaining the most complex legal issues to clients and the court.” Legal 500, 2022
“She has a no-nonsense approach to advocacy and is excellent on her feet. I have every confidence that she will achieve what she sets out to achieve.” Legal 500, 2021
“Great technical knowledge” Legal 500, 2020
“Gets to grips with novel subject matters very quickly” Legal 500, 2019
“She is extremely bright, gives pithy advice and is a tenacious advocate.” Legal 500, 2017
Awards
Education
ICO Data protection registration number: Z1653764.
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