Matthieu Gregoire > 4 New Square Chambers > London, England > Lawyer Profile

4 New Square Chambers
4 New Square

Living Wage

Work Department

International commercial arbitration ; investor-state dispute resolution ; commercial litigation ; public international law


Matthieu Gregoire is a barrister at 4 New Square Chambers specialising in international arbitration, public international law and commercial litigation.  He is routinely instructed in complex international commercial and investment arbitrations, across many industries and under a wide range of rules (including ICSID, SCC, LCIA, ICC, UNCITRAL and ad hoc Rules).  Matthieu acts as part of a team or as sole counsel.  He was appointed to the Attorney General’s Public International Law C Panel of Counsel in 2017.


Prior to joining the bar, Matthieu qualified as a New York Attorney and worked as an associate in the international arbitration team of Cleary Gottlieb, Steen & Hamilton, in Paris and as a consultant for the World Bank.  


English (native)

French (native)

Spanish (working knowledge)


Lincoln’s Inn


University of Cambridge (BA in Law)

Sciences Po, Paris (Masters in International Affairs)

Georgetown University (LLM)

Lawyer Rankings

London Bar > Public international law

(Leading Juniors)Ranked: Tier 2

Matthieu Gregoire4 New Square ‘Matthieu is a fantastic bilingual (English & French) lawyer with strong technical skills and business acumen. He is very good at identifying strengths and weaknesses in a case.’

London Bar > International arbitration: counsel

(Leading Juniors)Ranked: Tier 2

Matthieu Gregoire4 New Square ‘Matt is excellent in his analytical rigour, leaving no stone unturned. He is also a natural advocate who can tickle tribunal’s judgment bones easily.’

4 New Square ‘has really good strength in depth, both across their range of silks and their juniorsThe set’s members have experience of investment treaty disputes, commercial arbitrations and enforcement proceedings and challenges. A notable example of the latter was Province of Balochistan v TCC in which George Spalton KC acted for the claimant in challenging a £5bn award for lack of jurisdiction following ICSID and ICC arbitrations. Roger Stewart KC has a strong reputation and led Timothy Chelmick  and three more junior members in a major UK-based IT arbitration claim. Matthieu Gregoire  is a big name on the investment treaty side and is representing Sri Lanka in KLS Energy Lanka v Sri Lanka, a US$100m dispute arising from the cancellation of a wind and solar hybrid power plant project.

London Bar > Commercial litigation

(Leading Juniors)Ranked: Tier 5

Matthieu Gregoire  – 4 New Square ‘His attention to detail and teamwork is exceptional.’

4 New Square is ‘a top-class outfit with top to bottom strength‘. Core areas such as professional negligence also feed into the increasingly impressive commercial practice of its members. Recent high profile cases include Vneshprombank (VPB) v Bedzhamov & Ors in which Justin Fenwick KC is leading Mark Cullen, on behalf of Georgy Bedzhamov, who alleges he is the victim of a corporate raid in fraud proceedings brought by a now-insolvent Russian bank, against a backdrop of intervention of his own Russian trustee in bankruptcy. Daniel Saoul KC is also leading the team, including Matthieu Gregoire, on behalf of the claimants in 600 Claimants v Spence, Kewley, Crump & Others, in which hundreds of individuals and companies were allegedly mis-sold holiday and student properties through the defendant’s ‘Emerging Properties’ brand.