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Mark Twomey KC

Silk 2017 | Joint Head of Chambers


Described by clients as “at the top of the tree” Mark is a silk who handles difficult cases producing “lucid, measured and informed legal comment which induce total confidence”. Lawyers appreciate his “pellucid, cutting-edge legal thought”.

Chambers and Partners say that Mark is “Incredibly intelligent and brilliant in an understated way as he has it all carefully figured out. He’s very analytical and he will fight fiercely for the client even when you know all the odds are against you.”

Mark’s client-focused approach separates him from other silks. A charming and subtle advocate who delivers excellent client care, Mark has a genuine interest in his clients and works tirelessly to advance the best possible case for them. He has a reputation for being a trusted advocate – both to solicitors and judges – and for providing insightful and carefully analysed arguments. His approachable and calm advocacy style suits his clients in public child law and has enabled him to gain the trust of those clients he represents who are in the most difficult of personal situations.


Mark handles both public and private children law work including care and adoption issues, as well as finance matter such as TOLATA. Mark also advises local authorities and claimants in relation to Human Rights Act claims, particularly those involving Section 20.

Mark comes from a background in mixed common law and has specialized solely in family law for the last 12 years, before being appointed KC in 2017. His practice includes the most complex of cases, including those involving severe injuries, international movement of children and abduction, and BIIR. He regularly appears at all levels of court, including the Supreme Court and Court of Appeal, on landmark cases that become leading authorities in their areas.

His recent cases include:

  • A High Court case, pursuing grave findings on behalf of one of the two applicant Local Authorities, involving three parents and three guardians in a case relating to incest, sexual abuse and international child trafficking
  • Child trafficking in care proceedings, looking at conflict before child trafficking regulations and the obligations arising under BIIR, and the issue of habitual residence
  • A BIIR case, addressing the correct approach to applications made under Article 15 and involving the issue of international adoption rights in the UK, in particular the adoption of foreign nationals—do UK courts have the right to order the adoption of the children of foreign nationals against the parents’ wishes?
  • Cases of inflicted or accidental injuries, most recently one involving the poisoning of a child by salt
  • The correct approach, decided on appeal, to be taken to assessments of parents under section 38 [6] Children Act 1989
  • A Court of Appeal case relating to the Possession Order made following domestic violence in the family home

Mark is a leader in the field of family law, holding high level appointments in the family law community and frequently delivering training or commentary on contemporary issues in Adoption, Contempt of Court, BIIR and Abduction, including to the Local Government Lawyers Association, the ALC, to solicitors and within Chambers. He is interviewed regularly by the BBC in relation to legal issues concerning children.

Practice Areas

International Family Law

Private Law Children

Public Law Children

Human Rights

Local Authority

Education and Professional Memberships

Bristol University LLB 

Family Law Bar Association 

Association of Lawyers for Children 

Inner temple 


Family Law Bar Association Executive Committee  

Family Law Bar Association Co-Chair of FLBA Children Subcommittee 

Bar Council representative to MOG on effect of LASPO 


“A superb advocate, both in terms of oral argument and written work. Right at the top of his game. Mark commands the judges’ respect due to his highly tactical approach to his cases. Devastating in cross-examination and formidable in legal argument. An all round class act.” Legal 500, 2024 Ranked: Tier 2

“Mark Twomey KC is an all-round really great advocate. His handling of extremely complex children cases is really good and his advocacy is effortless.” Chambers and Partners, 2023

“Such a clever man, he knows the law so well and has a lovely way of presenting his case in front of  judges. Calm in his approach and never aggressive, he’s such a powerful advocate for his client.” Chambers and Partners, 2023

“Mark has a gloriously eloquent manner and is remarkably persuasive in court. He’s obviously highly intelligent but also has immense charm which he uses to good effect in his advocacy.” Chambers and Partners, 2023

“Mark is a wise, considered, knowledgeable, and empathetic barristers and truly a good person.” Legal 500, 2023

Mark Twomey KC has “unrivalled knowledge and skills in children law’ and acted in Supreme Court case Re T, related to deprivation of liberty of children after a child was locked up by a local authority in an unregistered children’s home” Legal 500, 2023

“An amazing advocate with a quick brain and a lovely turn of phrase who has the ear of the court.” Chambers and Partners, 2022

“His submissions are of the highest quality. He grabs hold of difficult cases and produces pellucid, measured and informed legal comments which induce total confidence.” Chambers and Partners, 2022

“His presentation in court is smooth, persuasive and utterly effortless.” Chambers and Partners, 2022

“Thank you to Mr. Twomey – he was brilliant.”, Private client solicitor 

“Very grateful for Mark’s excellent advice and representation”, Local authority solicitor 

“We have felt so very well supported by your excellent representation, your position statements have always reflected clearly our view and approach and you could easily sense the mutual respect between yourself and the Judge, which I know has contributed positively to this outcome as she has trusted that whatever position you put forward on behalf of the LA, it was well thought through and thoroughly analysed. I felt you have been a great advocate for us, keeping a calm approach during the hearings which gave myself and my team great reassurance.”, Local authority solicitor  

Publications and Training


“No child transfer to the EU under Article 15 BIIR without a best interests analysis of its effects on the child” Considering Re N (Children) [2016] UKSC 15. Family Law Week 2016 

“Hair testing for illicit drug use” World Sports Advocate: Volume 5, Issue 7, July 2017. 


Presenter: Public Children Law update at ALC Conference 2018 

Presenter: Coram Conference 2018 – Brexit for Breakfast: Impacts of Brexit on family law in the UK, opening session 

Chair: NAGALRO Autumn Conference 2018  

Presenter: White Paper Public Children Law Conference 2018 

Advisor to Supreme Court of Kazakhstan on the English family court model 2018 

Lecturer on adoption, contempt of court, Brussels II and child abduction to Local Government Lawyers Association, ALC, and family law solicitors 

Presenter: Family Rights Group Conference 2017 

Presenter: Public Children Law update at ALC Conference 2017 

Presenter: Coram Conference 2017 – Bursting the Bubble: Legal update of non-family law cases for family lawyers, opening session 

Presenter: LexisNexis Family Law Update 2017 

Guest on BBC for various interviews re: legal issues surrounding children 


Supreme Court 

Williams and another v London Borough of Hackney [2018] UKSC 37 

Re N (Children) 2016 [UKSC 15] 

 Court of Appeal 

T (A Child) [2018] EWCA Civ 2136 

Re N-S (Children) [2017] EWCA Civ 1121  

Re DAM (Children) [2018] EWCA Civ 386  

Re A (Children) [2018] EWCA Civ 1718 

 High Court / Family Court 

Re L (A Child) [2017] EWHC 3707 (Fam) 

W (A Child) [2017] EWFC B48  

LB Merton vs SB & Ors [2017] EWFC B81   

R v P [2017] EWHC 3797 (Fam)  

C (A Child) (No. 3) [2017] EWFC 37  

NAA (A Child) [2017] EWFC B76  

Re C (A Child) (No 2) [2017] EWHC 692 (Fam)