Our collegiate approach to practice enables us to offer an integrated service across all areas with client care at its heart.

Our Story

We are a full-service commercial law firm with offices in the City of London and New York. We offer expertise comparable to magic circle firms but with a personalised and agile approach, all at a competitive cost. Established in 2016 by Arianne King and Julian Critchlow, who have collectively accumulated over 50 years of experience working in the top, most reputable central London law firms.

After working together for 10 years, Arianne and Julian shared a desire to create a law firm to service their specialist areas of expertise and allowed them to serve their clients with outstanding results, alongside a carefully chosen team. We have the capacity to handle complex cases, maintaining the agility to act swiftly and provide a personalised service.

Our clients instruct us for expert legal expertise, knowledge, and commercial acumen. When we receive instructions, we assemble a specialised team comprising highly effective professionals. With our extensive experience, we remain committed to delivering the best available outcomes while adopting a flexible and business-oriented approach.

Our Expertise

High-value dispute resolution, including litigation, arbitration, adjudication and mediation for both corporations and individuals, both internationally and domestically.

Handling corporate and commercial transactions, such as mergers and acquisitions, company formations, restructuring, and company listings, both internationally and domestically.

Expertise in Gaming and Betting as well as Regulatory Governance and Investigations.

Handling transactional and dispute work relating to Energy, Infrastructure, Construction, and Engineering both internationally and domestically.

Why work with us?

Advice you can understand

Whether it’s advising in-house counsel or clients directly, we ensure that our advice is clear and understandable.

Flexible fee structures

We adopt flexible fee structures to ensure you get access to magic circle experience at a price that works for you.

Commercial focus

We pride ourselves on working in our clients’ best commercial interests.

Competitive costs

We want our clients to have access to magic circle advice without the magic circle cost to ensure they get the best value for money.

Efficient & transparent

No hidden costs and no “overlawyering”. We assign a bespoke team that will give you the advice you need. Nothing more, nothing less.

Personable & Approachable

We have a very special ethos. We combine the highest professional standards with a welcoming atmosphere which extends to our clients, many of whom have become close friends.

  • "In a world where law language is the opposite of tech language, Costigan King always make time to break down the complexities and help us understand the detail. Friendly, approachable and efficient."

    Robbie Morris, Director, Two Up Digital

  • "Costigan King is our key port of call for construction matters. Carl Asser's exceptionally client-friendly approach always strikes the right balance of commercial and legal advice in a way that the business needs and loves. Carl is a trusted expert who understands the needs of the business, cutting through complex legal matters to deliver pragmatic advice in an intelligent and efficient way."

    Toyota Plc

  • "Working with Costigan King is an all round seamless process. No action is too small or request too big once their services are engaged. Highly coveted legal expertise with a personal touch. They have been integral to getting our business off the ground, I look forward to working with them in the future."

    Darren Michael, Founder, Renewable Infrastructure Network

  • "Arianne & her team handled the sale of our European marketing business to a large US firm. The sale, & subsequent 3-year earn-out, went smoothly thanks in large part to the excellent job they did in protecting our interests & diligently & efficiently handling all legal aspects of the transaction."

    Mike King, Eleven Hundred Agency

Contact us

If you would like to contact us, please complete the form on how we can assist you and we will be sure to contact you.