Cleon Catsambis has a broad and successful commercial practice that encompasses commercial litigation and dispute resolution, banking & financial services, fraud and regulatory & disciplinary law. He also practises in administrative and public law.
Cleon applies his commercial nous, robust legal analysis and strong advocacy skills to each of his cases in order to achieve the best possible outcome for his clients. He regularly appears as sole and junior counsel in high-value and complex disputes in the High Court, the Court of Appeal and a variety of Tribunals. He also undertakes pleading and advisory work.
He is an editor and contributing author to a number of publications, including Atkin’s Administrative Court Practice, Jordan’s Regulatory and Disciplinary Proceedings and Butterworths Financial Regulation Service.
Cleon undertakes pleading and advisory work and represents clients in all types of commercial cases, from simple contractual disputes to high-value complex multi-party litigation with an international dimension.
He has particular experience of banking & financial services, fraud and professional negligence claims, as well as applications for interim relief including freezing orders, search orders and general matters relating to disclosure and legal professional privilege.
Cleon’s cases often entail an international dimension, and he has experience of jurisdictions including the Russian Federation, Cyprus, the Netherlands, the Bahamas, the Cayman Islands and Jamaica.
Cleon accepts instructions in all types of commercial cases, including:
Notable experience includes:
Cleon is a pro bono volunteer at the Bar Council’s CLIPS scheme of the Chancery Bar, as well as of the Queen’s Bench Division, advising and representing pro bono clients.
Cleon regularly advises and acts for firms, investors, banks and regulators on the full range of issues arising under the domestic and European/international legal framework, including compliance and enforcement, judicial review, professional negligence, mis-selling claims and collective investment schemes.
In 2014, Cleon worked in-house with the Enforcement and Financial Crime Division of the Financial Conduct Authority, concentrating on consumer credit issues. He advised the FCA on the interpretation and application of their statutory powers and considered the legal dimension of applications for authorisation.
Cleon was involved in the case of Conlon v Black Horse  CTLC 193, which was ultimately determined by the Supreme Court in November 2014 (Plevin v Paragon Personal Finance Limited  UKSC 61) and is the leading authority on the proper application of s.140A of the CCA 1974. On the back of that, Cleon has been involved in successful applications for permission to appeal based on the decision in Plevin and has advised both firms and individuals on the proper application of the unfair relationship regime.
Recent notable work includes:
Cleon has had extensive involvement as a s.166 FSMA skilled person in a major review into the mis-selling of interest rate hedging products by two high-street UK banks.
Cleon is a contributing author to Butterworths Financial Regulation Service.
Cleon has considerable experience in regulatory law, particularly in the financial services and healthcare sectors. He advises and acts for regulatory and professional bodies, government departments, firms and individuals. Cleon is a contributing author to the 8th edition of Jordan’s Regulatory and Disciplinary Proceedings (2015).
Cleon practices in all areas of financial services regulation. For further details please see the Banking & Financial Services section of his profile.
Cleon regularly advises and acts for most major regulatory bodies including the Health and Care Professions Council (having acted in over 30 High Court applications and appeals), the General Medical Council, the General Dental Council and the General Optical Council. Cleon was involved in the judicial review concerning the national reorganisation of paediatric cardiac surgery centres (R (Save our Surgery Ltd) v Joint Committee of Primary Care Trusts  EWHC 439 (Admin)). In 2012, Cleon undertook a secondment at Monitor, the regulator for NHS Foundation Trusts. He also advises on the provider licence conditions, the enforcement regime and statutory interpretation.
Other regulatory experience
Cleon has also:
Cleon’s practice encompasses complex construction and infrastructure disputes. He has recently advised the UK government on a multi-million pound latent defects claim in respect of military facilities (as sole counsel). He has also acted in a high-value nuclear infrastructure dispute involving issues of delay and disruption, termination, professional negligence and contractual interpretation.
Cleon has a busy public law practice, encompassing civil liberties and human rights, immigration and asylum, education law, healthcare and mental health.
He is the Editor (with Hodge Malek QC and Saima Hanif) of Atkin’s Administrative Court Practice.
Cleon has extensive experience in judicial review proceedings and has been involved in the following notable cases:
Cleon’s experience further includes:
In matters of education law, Cleon regularly advises and represents schools, local authorities and parents on a wide range of issues including admissions appeals and infant class size appeals.
Cleon also assisted Jonathan Cooper OBE of Doughty Street Chambers in delivering the week-long Advanced Human Rights Law Training Programme for senior Foreign Office policymakers and diplomats.
Cleon has a particular knowledge of and experience in the aviation sector. He regularly advises and acts for the Civil Aviation Authority, individual airports and airlines.
Cleon acted for the CAA in the judicial review proceedings concerning its duty to consult in respect of alterations to air traffic control patterns on the Westerly approach to Gatwick Airport (led by Gordon Nardell QC): R. (on the application of Barraud) v Civil Aviation Authority (Queen’s Bench Division (Administrative Court); 31 July 2015).
He has also advised the CAA in respect of airspace changes, consultation duties and post implementation reviews in respect of Gatwick Airport, London City Airport, Luton Airport and Edinburgh Airport.
Cleon has also advised multiple international airports on, among other things, the lawfulness of consultation exercises, environmental impacts and trials of new SIDs.
Cleon was involved in the litigation concerning Ryanair’s minority shareholding in Aer Lingus and whether it complied with EU and domestic merger regimes.