Andrea McMahon Partner

Speaks:  English

Qualified: 1999 - Solicitor of England & Wales

Called to the Bar: 1998 - England & Wales

Primary office:  London

Andrea McMahon

Andrea uses her extensive and varied public sector expertise to help clients through challenging litigation, inquiries/reviews, investigation work and associated policy issues. As a former Senior Civil Servant, she has spent almost 20 years in the Government Legal Department and Cabinet Office advising Secretaries of State, ministers, Permanent Secretaries and senior officials on a range of sensitive and high profile matters. Her investigation work is unprecedented in terms of complexity, scale, political and public interest, and conducted with the highest degree of integrity. Andrea also has a wealth of experience in complex judicial review litigation, including challenges to decisions on appointments to the highest levels of government, and leadership of large teams in a litigation context.

Andrea is responsive to the needs of her clients, offering pragmatic advice in difficult contexts. Participating in litigation, investigations, and inquiries can be challenging and stressful experiences for clients, whether they are government departments, corporate entities or individuals. Andrea has been widely praised for her ability to guide clients and wider stakeholders through very difficult and complex challenges with sensitivity and understanding whilst remaining forensic in her approach. Not only does she fully understand the legal implications for those she supports but also the wider impact of the approach taken on her clients and society.

Andrea's unique experience working with policy teams in the Cabinet Office enables her to recognise when problems require more than purely legal solutions, offering her wider perspective resulting in workable strategies. She is known for her strength in strategic focus, forensic approach and delivering outcomes in challenging circumstances. Helping her clients to manage risk and reputation, she recognises the risks of negative media experiences and is proficient in assisting clients to guard against them.

Andrea is a team player who goes the extra mile and has a strong track record of working successfully in intense and complex political contexts. She offers a high level of personal support, constructive challenge and respected advice, quickly establishing trusted relationships. She has very strong stakeholder management skills and is acutely aware of the wider impact that decision making and legal challenge can have on individuals and the public at large.

Having chaired the Government Litigation Training Group for seven years, Andrea is experienced in personally delivering training sessions and led the delivery of the annual training programme for Litigators. She has vast experience in government disclosure, including the duty of candour, and litigation strategy having jointly led a project to collate best practice and knowledge across government departments.



  • Supporting and advising government departments and significant individuals, including Secretaries of State and senior officials at various stages of statutory public inquiries/reviews (Independent Inquiry into Child Abuse (IICSA), Leveson inquiry/Chilcot Inquiry/COVID-19 Inquiry).
  • Leading, coordinating and supervising government teams in relation to the provision of evidence and support/advice to government and former government witnesses (including several members of the House of Lords). Including advice and leading on coordination/approach/drafting statements and oral evidence to an inquiry. Andrea's role ensured coordination and provided the inquiry with the appropriate range of evidence required to achieve the Inquiry objectives whilst supporting the Government.
  • Personally advising and leading government teams to fully support high-profile witnesses and Secretaries of State/Core Participants when providing significant evidence to statutory inquiries. Coordinating disclosure, leading policy teams, drafting statements, preparing for oral evidence and liaising with wider government teams. The inquiry Chair commented positively on the preparation of the evidence and its usefulness to one such inquiry.
  • Successfully supporting a significant individual in the representation process (Maxwellisation) of a high profile inquiry, assisting the inquiries and reviews to understand the specific roles of the relevant witness, leading to proposed criticism being removed or severely curtailed.
  • Personally supporting and advising a serving minister and member of the House of Lords in relation to the provision of witness evidence to a high profile inquiry. The advice and comprehensive approach taken meant that the witness was not required to provide oral evidence.
  • Advising and supporting the former Director of Inquiries in the Cabinet Office in relation to the provision of information/disclosure and the approach to the provision of witness evidence.
  • Advising government ministers in relation to issues arising in a high profile inquiry. Providing advice relating to investigations/disclosure and strategic responses to enable departments and ministers to prepare documentation and media lines.
  • Leading the team for the Ministry of Defence providing support, advice and representation in high profile inquests.


  • Leading and undertaking high profile and sensitive investigations, including relating to sensitive conduct matters and professional standards, across government providing support and advice to Ministers, Permanent Secretaries and senior officials.
  • Identifying and developing policy changes and interventions to drafting policy/approach to investigations to embed fair and robust processes.
  • Advising on investigative strategy, drafting Terms of Reference and associated protocols to ensure fair processes.
  • Drafting investigation reports, findings and recommendations in a wide range of investigation work. Advising departments, senior officials and Ministers regarding outcomes and next steps leading to changes in culture and behaviours.
  • Experience of working in policy across ethics and integrity issues in government. Working closely with government ministers on matters relating to behaviour/conduct and safeguarding on the Westminster estate.
  • Experienced in representation processes (Maxwellisation) in investigation work.


  • Extensive and wide ranging litigation experience including judicial review and private law matters involving complex legal issues in several areas: European Convention on Human Rights (ECHR) law and domestic law, international humanitarian law, the law of conflict, immigration, public appointments and other areas.
  • Leading and developing policy/legal approach to high profile public law claims against the Cabinet Office and very senior Ministers in relation to challenges relating to the application of codes of conduct and making of appointments. Providing expertise and advice to departmental boards regarding cross-Whitehall litigation.
  • Leading complex group actions involving unlawful detention cases, public interest immunity and closed material proceedings. Leading on strategy across private law litigation arising from the Iraq and Afghanistan wars. Cases spanned Administrative Court, Court of Appeal, Supreme Court and European Court of Human Rights.
  • Lead on litigation strategy and coordination/approach to group actions and expertise in large settlement projects including setting up schemes for triaging and assessment of causation and quantum. Experienced in round table discussions and negotiating settlement.
  • Experience in dealing with related judicial review litigation arising out of inquisitorial work and appointments at the highest level in government.
  • Advising on Public Interest Immunity, Closed Material Proceedings and other sensitive matters arising in relation to dealing with sensitive material.
  • Leading approach and government responses to sensitive information requests and investigations involving the Information Commissioner. Handling, advising and supporting witnesses in relation to Information Tribunal hearings. Drafting submissions to ministers and assessing the public interest in the provision of information.
  • Experienced in delivering and organising training for lawyers and clients. Chair of the Government Litigation Training Group for seven years. Extensive understanding of government litigation strategy having jointly led a project to collate best practice and knowledge across government departments.


Andrea brings a laser like focus and clarity to the wide range of complex and often sensitive issues on which we worked together. She has the ability to centre in on the issues that matter and develop pragmatic advice and solutions that take account of the multiple and sometimes competing interests involved. She has an acute sense of the political and wider context, her judgment is impeccable and she operates with the upmost integrity and emotional intelligence.

Andrea was an invaluable asset to the inquiries team, providing timely, robust and pragmatic advice on a range of issues and topics.

She is very committed, energetic, and helpful, really good professional skills and judgement.

Commitment to her [inquiry witness] deserves special praise.

Andrea has provided exemplary support to the [X] and [Y] and has been instrumental in guiding individual issues to successful resolution….

Andrea is trusted implicitly. She consistently provides accurate and timely advice in pressured situations that allows us to respond proactively to just about any legal situation which arises. This is because she has made it her business to understand our business...she is a highly valued and respected business partner.

Crucial to her contribution was a combination of professional litigation skills, commitment to working closely with the client and the ability to devise and drive through a legal strategy, carrying her colleagues and counsel with her. All of this was underpinned by relentless energy and a commitment to the client's interests while operating with integrity….'

Andrea has an excellent ability to recognise the strengths and development needs of the people around her and is committed to providing guidance and help to develop them. She is very supportive of her team; she is engaging and collaborative.

She is a very credible confident leader with particular marked strengths in strategic focus and delivery. She quickly builds candid and effective relationships with Seniors.

Andrea is a respected leader who actively and visibly supports her team, she can be tough and challenging when circumstances require that style of approach.

Andrea possesses excellent stakeholder management skills - she engages regularly and adopts a collaborative approach which results in highly productive relationships.

Career & Recognition

Filter timeline:
  • 2022

    • Career
      September 2022
      Gowling WLG (UK), Partner
  • 2019

    • Career
      March 2019
      Cabinet Office, Senior Civil Servant Deputy Director Propriety & Ethics Team
  • 2009

    • Career
      Government Legal Department, Senior Civil Servant Deputy Director
  • 2007

    • Career
      Government Legal Department, Senior Lawyer
  • 2003

    • Career
      Government Legal Department, Lawyer
  • 1999

    • Qualifications (Year of Call/Admission, etc.)
      Qualified, Solicitor of England & Wales
  • 1998

    • Qualifications (Year of Call/Admission, etc.)
      Called to the Bar, England & Wales