William O’Brien

Senior Associate

Areas of Expertise

William specialises in the avoidance and resolution of disputes, particularly involving development and construction. He joined the Construction, Engineering & Procurement team in July 2020 having trained at the firm and qualifying into its Litigation & Dispute Resolution department. He has a broad range of experience of bringing, defending and resolving claims through adjudication, litigation, arbitration, expert determination and alternative dispute resolution (ADR). A significant part of William’s practice involves advising clients in situations where disputes are anticipated in the future and how to avoid them. He acts for companies, social housing providers and private individuals.

Experience

During his training, William sat in Devonshires’ Property Litigation and Real Estate departments. He previously worked as a paralegal in local government and gained experience of planning, property and development, as well as governance.

Publications

Insolvency cover clarified – Peabody Trust v NHBC (Local Government Lawyer, September 2024)

Challenging CVAs as a creditor (Local Government Lawyer, June 2023)

William regularly publishes insights on Devonshires’ website on a range of legal topics connected with construction and development.

Directories

Key lawyer – Planning (Legal 500, 2025)

Key lawyer – Construction: Contentious (Legal 500, 2024)

Education

William took an Upper-Second class degree in Laws (LLB Hons) at UCL, where his addressed restorative justice in criminal law. He achieved a Distinction in his LLM in Legal Practice at the University of Law, Bloomsbury, where his masters dissertation critically analysed the history and future of planning law.

Personal

Prior to becoming a parent, William ran half-marathons. Now, he runs 500m sprints after his two young children.

Awards

William won the René Cassin Human Writes Essay Competition 2018 and was given an honourable mention for his entry into the UK Environmental Law Association’s annual essay competition, the Andrew Lees Essay Prize 2018.

He was awarded a Choose Law scholarship while studying for his LLM at the University of Law, Bloomsbury (2016-17), achieved the second highest grade in his Jurisprudence module on his undergraduate law degree at UCL (2012) and was awarded his Sixth Form’s Politics Prize (2009).

Notable Cases

William acted for Peabody Trust in its successful defence of a reverse summary judgment application on grounds of limitation ([2024] EWHC 2063 (TCC)). William also successfully resisted an appeal of that decision by NHBC to the Court of Appeal ([2025] EWCA Civ 932).

William acted for Catalyst Housing in its successful application for security for costs in a planning and overage dispute ([2022] EWHC 701 (TCC)).

William regularly acts for insolvency practitioners seeking relief under the Insolvency Act 1986 and enforcing security (examples include Reynolds v Tifrit (2024, unreported); Re Systems Building Services Group Ltd [2020] EWHC 54 (Ch); Pantiles and another v Winckler [2019]).

William acted in a successful claim to a £35m fund which has laid dormant since 1948 in a complex and high-profile case involving two governments as parties (High Commissioner for Pakistan in the UK v Prince Muffakham Jah and others [2019] EWHC 2551 (Ch)).

Client Testimonials

“I was impressed by senior associate William O’Brien’s attention to detail; he knew the facts of the case inside out. He also had good instincts on the legal arguments.”