Sean O"Sullivan KC > 4 Pump Court (Sean Brannigan KC and Rachel Ansell KC) > London, England > Lawyer Profile

4 Pump Court (Sean Brannigan KC and Rachel Ansell KC)
4 Pump Court


Sean is a widely acclaimed commercial silk at 4 Pump Court, whose practice spans a wide range of shipping and energy disputes as well as related insurance and reinsurance claims. Sean is highly experienced in charterparty disputes, bills of lading contracts, sales of goods and shipbuilding disputes. He is regularly instructed by shipyards, buyers, owners and designers as well as oil companies, traders and contractors. As well as his counsel work Sean also accepts appointments as an arbitrator. He is recommended as a leading silk by mainstream legal directories for Shipping, Commodities, Energy, Insurance/Reinsurance and International Arbitration.


Qualified 1997, Middle Temple; Silk 2014; Recorder 2015. Authorised to sit as a Deputy High Court Judge 2020.


COMBAR; TECBAR; LMAA (supporting member); LCIA (European Users Council).


Oxford (MA); City University (Dip Law).


Golf, theatre, music.

Lawyer Rankings

London Bar > Energy

(Leading Silks)Ranked: Tier 2

Sean O’Sullivan KC4 Pump Court ‘Extremely bright but also pragmatic and approachable, he has an uncanny ability of keeping Tribunals on-side and keeping the bigger picture in mind.’

4 Pump Court is ‘user-friendly and unpretentious, with a strong energy team, especially for upstream work and in the offshore arena’. The set has ‘a high reputation in this area and has lots of members with wide expertise’. It has particularly strong expertise in energy infrastructure matters, drawing on vast experience in related areas such as construction and engineering, shipping, insurance and professional negligence. Its members, among them standout silk Sean Brannigan KC, act for energy companies, engineers, funders, governments, operators and sub-contractors in an advisory capacity and as advocates in all forms of dispute resolution in the UK and internationally. Brannigan represented a large construction management firm in claims and counterclaims with a value in excess of $650m arising from the design and construction of the world’s largest single-phase petrochemical plant in the Middle East. Prominent silk Sean O’Sullivan KC handled the hard fought dispute BP v Galtrade, concerning the consequences of a delivery of off-spec fuel oil in the context of complex blending operations. Outstanding junior Thomas Crangle acted in a TCC dispute between Seflam and Nigerstar relating to the upgrade of a major oil pipeline on the Nigerian coast.

London Bar > Insurance and reinsurance

(Leading Silks)Ranked: Tier 5

Sean O’Sullivan KC4 Pump CourtCalm and assured.

London Bar > International arbitration: counsel

(Leading Silks)Ranked: Tier 2

Sean O’Sullivan KC4 Pump Court ‘He is highly responsive, incredibly diligent and well-prepared. He is happy to roll his sleeves up and get onboard. His advocacy is excellent, he strikes just the right tone, is persuasive and enjoyable to watch.’

4 Pump Court is a ‘very strong set of barristers for complex document heavy arbitrations‘  and is commended for its ‘good strength in depth, in both the Silk and junior stables’. The set stands out for its versatility, with members offering excellent expertise in a range of key industries, including construction and engineering, IT, shipping and insurance. Members regularly work in teams or appear on opposite sides. Recently Sean Brannigan KC has faced off against Rachel Ansell KC in a major multibillion-dollar infrastructure dispute in the Middle East. Sean O’Sullivan KC is also leading Andrew Stevens in a significant cross-border shipping claim involving Chinese and Indian parties.

London Bar > Shipping

(Leading Silks)Ranked: Tier 2

Sean O’Sullivan KC4 Pump Court

With a deep bench of practitioners, 4 Pump Court remains a go-to set for clients in the shipping sector and handles disputes in the Commercial and High Court as well as in arbitration. . James Leabeater KC and Rani Noakes acted on behalf of the appellant disponent owners and Alexander Wright KC, who took silk in 2022, was instructed by the respondent voyage charterers in The Tai Prize, where the Court of Appeal upheld the High Court decision that voyage charterers are not liable towards owners for losses caused by an inaccurate bill of lading. Whether a marina as a whole could be defined as a dock for the purposes of limitation was the central question in Holyhead Marina Ltd v Farrer and Others, in which James Watthey acted on behalf of insurers and owners of damaged vessels. Sean O’Sullivan KC continues his involvement in a number of high-profile cases, including CV Stealth about a vessel that was detained in Venezuela after an attempt to export oil from the country, which the government alleges was a breach of local law. Thomas Steward, whose practice encompasses international arbitration and commercial litigation in shipping and shipbuilding, joined the set from The 36 Group in 2022, while Neil Henderson left for an in-house position at Gard AS the same year.

London Bar > Commodities

(Leading Silks)Ranked: Tier 2

Sean O’Sullivan KC4 Pump Court ‘His advice is strategically sophisticated but lucidly explained to clients, and his advocacy gains respect from judges and counsel alike.’