Harry O’Sullivan

Harry O’Sullivan

Call: 2016

Interested in instructing Mr O'Sullivan?

Please call 020 7353 6802 or complete the form below:

Harry O’Sullivan is a specialist criminal barrister who accepts instructions to both defend and prosecute the full range of criminal cases.

Harry has a particular interest in sentencing law. He is the author of Banks on Sentence, the leading practitioner text on the subject and is the consultant editor of Halsbury’s Laws of England latest sentencing and offender management volumes. Before coming to the Bar, Harry worked at the Law Commission of England and Wales on the project which produced the Sentencing Act 2020.

He is authorised to conduct work on a direct access basis and is appointed to the CPS Advocate Panel at Grade 3. Harry also accepts instructions in matters of prison law, military law, to appear in inquests and inquiries and has experience of private prosecutions.

Harry plays an active role on the South Eastern Circuit committee and was circuit junior 2023. He is also Chambers Secretary and a member of Chambers’ Pupillage and Tenancy Committee.


Interested in instructing Mr O'Sullivan?

Please call 020 7353 6802 or complete the form below:

Crime Barrister

Harry is regularly instructed to appear in the Crown Court in London and the South-Eastern circuit. He is appointed to the Crown Prosecution Service advocate panel scheme at grade 3 and has experience in private prosecutions.

As the author of Banks on Sentence, Harry has specialist knowledge of complex sentencing legislation and procedure and is happy to accept instructions to advise on appeal against sentence on a direct access basis. Harry accepts instructions to provide advice and representation before the Parole Board in matters of prison law and is regularly instructed to represent offenders and the Secretary of State.

Harry’s experience also extends to representing parties in regulatory appeals to the magistrates’ court and military law matters before the Court Martial.

Notable Cases

  • Essex County Council Trading Standards v D – Southwark CC 2023: led junior for the defence in a multi-handed conspiracy to defraud trial lasting three months.
  • R v AH and Others – Inner London CC 2022-2023: instructed as led junior for the Crown in a five-handed fraud and money laundering trial involving organised impersonation attacks against a major bank and its customers.
  • R v AS – Basildon CC 2023: prosecution counsel in trial of fraud committed against vulnerable people duped into handing cash to individuals falsely claiming to be police officers.
  • R v GG – Kingston CC 2023: prosecuted trial of issue in relation to GBH against a prison chaplain by a defendant found to have paranoid schizophrenia. Hospital order with restriction imposed.
  • R v UI – Cambridge CC 2023: secured the acquittal of a defendant alleged to have conspired to supply class A drugs after a successful abuse of process argument.
  • R v MP – Swindon CC 2023: secured a Community Order for defendant accused of involvement in a county-lines drug dealing conspiracy.
  • MPS v MS – Highbury Corner MC 2022: successfully resisted a police application for a stalking protection order.
  • R v EA – Kingston CC 2022: secured acquittal for defendant accused of controlling and coercive behaviour in a family relationship.
  • R v JWB and others (Operation Alatyr) – Central Criminal Court 2020-2021: instructed as led junior for the Crown in a seven-handed case involving the seizure of significant quantities of class A and B drugs and firearms.
  • R v EM – Luton CC 2022: prosecution counsel for a trial involving demonstrating the defendant’s use of a mobile phone inside a prison by reference to complex expert evidence and subscriber data.
  • R v DC – Inner London CC 2022: prosecuted trial of issue in relation to a vulnerable defendant who was found to have kidnapped a child.
  • R v MS – Reading CC 2021: secured the acquittal of defendant accused of unlawful wounding.
  • R v MT – Southwark CC 2021: prosecution counsel in a robbery trial involving the organised theft of high-value luxury watches by criminal gangs.
  • R v SL – Wood Green CC 2020: Represented a vulnerable defendant throughout proceedings involving serious sexual offences against a child.
  • Central Bedfordshire Council v GD – Luton CC 2019: Instructed on behalf of Trading Standards to prosecute allegations of a substantial fraud committed against a small business.
  • R v Craftsman Q – Bulford Military Court Centre 2019: Represented a defendant before the Court Martial for ABH charges.
  • R v PS – Norwich CC July 2019. Prosecution for possession of a bladed article in a prison.
  • R v CH – Basildon CC 2019: Prosecution for possession of multiple machetes in a public place.
  • R v Fusilier JT – Bulford Military Court Centre 2018: Obtained a service supervision and punishment order following a plea to an Armed Forces Act offence at Court Martial.


R v D [2019] Crim LR 436 – concerning the definition of a folding pocketknife for the purposes of Criminal Justice Act 1988 s 139.

When is a residential address a dwelling for the purposes of sentencing?’ (2017) 2 (Aug) Sentencing News 6-9.

The Sentencing Code’ (2017) 181 (29) Criminal Law & Justice Weekly.

Time For A Code: Reform of Sentencing Law in England and Wales’ European Journal of Law Reform (2017) 19)4) – with Professor David Ormerod QC.

Inquests and Inquiries Barrister

Harry is a member of Goldsmith Chambers inquest team and accepts instructions to represent and advise interested persons and represent them before Coroners’ inquests and public inquiries.

Notable Cases

In the matter of the inquest touching upon the death of AM – Berkshire Coroner’s Court – May 2018. A pre-inquest review at which it was successfully argued that the state’s Article 2 duty would only be discharged by a full ‘Middleton’ inquest.

Extradition Barrister

Harry is keen to develop a practice in the field of extradition law and is happy to accept instructions to advise and represent requested persons at extradition hearings and appeals, as well as to act on behalf of requesting states for the Crown Prosecution Service.

Michael Johnson

Find the right barrister

Please contact Michael Johnson one of our Clerks, who will advise you on the best representation for your requirements and budget. Please call on 0207 427 7173 or email.

Education & Qualifications

  • BPTC (Outstanding), University of Law (2015-16)
  • LLB with European Legal Studies (Upper Second-Class honours), King’s College London (2011-15)
  • Diploma of European Union Legal Studies (Very good), University of Toulouse (2014)


  • CPS Advocate Panel at Grade 3
  • Criminal Bar Association
  • South Eastern Circuit (Circuit Junior 2023)
  • Gray’s Inn



  • Francis Bacon Award, Gray’s Inn (2015)
  • Routledge Book Prize, King’s College London (2015)
  • University of Law Selection Event Award (2015)
  • James Hunt Prize for Advocacy, Gray’s Inn (2018)
  • Ann Goddard Pupillage Scholarship, Gray’s Inn (2018)

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regulated by the Bar Standards Board

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