About

Simon specialises in competition litigation and collective actions, and has extensive experience of advising in relation to both High Court trials, proceedings in the Competition Appeal Tribunal and alternative forms of dispute resolution.

He has particular experience of group litigation, both in the context of commercial disputes and in private damages actions for competition law breaches.

His practice includes co-ordinating and advising in relation to English law issues arising out of overseas proceedings, as well as in proceedings brought in the English courts, and he advises corporates, international banks and private wealth funds as well as certain high-net-worth individuals.

Simon is ranked in the Legal 500, Chambers and Partners and Lexology Index (formerly Who's Who Legal)  for competition litigation.

Experience

  • Advising Performing Right Society in relation to proposed collective proceedings alleging anti-competitive conduct in relation to the distribution of musical royalties.
  • Advising Prysmian in relation to various damages actions and collective proceedings brought against a number of Defendants concerning anti-competitive conduct relating to EC Decision AT.39610 (Power Cables).
  • Advising a major international bank in relation to private damages actions and collective proceedings brought against a number of Defendants arising out of anti-competitive conduct in relation to foreign exchange.
  • Advising a client in relation to multiple private damages actions and collective proceedings brought against a number of Defendants concerning EC Decision AT.39824 (Trucks).
  • Advising a client in relation to private damages actions in relation to certain patent settlement agreements.
  • Advising a commercial enterprise in relation to its potential exposure to the LIBOR investigations.
  • Advising a group of companies including UK plcs and other private companies in relation to allegations of unlawful means conspiracy, breach of the Data Protection Act, breach of confidence and defamation (Various Claimants v Sir Robert McAlpine & others [2015] EWHC 3543 (QB)).
He is good at catching the intellectual high points, is a good listener and offers valuable strategic oversight.

Chambers UK 2026

Simon Day is exceptionally thoughtful in providing advice to clients and is a strong strategic litigator.

Chambers UK 2026

Simon Day - erudite and creative lawyer, who goes the extra mile for his clients.

The UK Legal 500 2026

Simon Day is a great litigator with a lot of experience in collective proceedings and is smart and pleasant to work with.

Chambers UK 2026

Simon Day is an enormously experienced disputes lawyer, both technically and from the point of view of giving strategic advice in hugely complex litigation.

Chambers UK 2026

Simon Day is exceptional and has the rare talent of keeping a calm head while fiercely advocating for his client’s interests.

The UK Legal 500 2024

Case studies

Insights and news