Leigh Day is a British law firm founded in 1987 by Sarah Leigh and Martyn Day. It has come to play an almost constitutional role in Britain: when the government acts, Leigh Day is often ready to oppose. It is a big beast in the world of right-on claims, with the capacity to represent thousands of claimants at once.
Leigh Day relies heavily on "no win, no fee" cases, meaning it eats only what it kills. It is one of the few major legal firms in Britain not to be a limited partnership, meaning if things go wrong the partners are personally on the hook. Critics see the firm as a glorified ambulance chaser; by all accounts it is a delight to work for and a nightmare to come up against.
Birmingham City Council is near bankrupt due in part to a series of equal-pay claims led by Leigh Day, with courts deciding that cleaners should earn the same as binmen. The firm launched the biggest environmental class action in British history in October 2025, targeting polluters of the River Wye. It represents the families of Afghans allegedly killed by British special forces. It previously represented Iraqi civilians claiming abuse by the British army; the civilians turned out to be members of a militia. The firm was dubbed "tank-chasers" in the press and Mr Day was dragged before regulators, but he was cleared of any wrongdoing.
Mr Day is a former chairman of Greenpeace UK. Richard Hermer, Britain's attorney-general under Labour, was Leigh Day's go-to barrister for years. Keir Starmer, a former human-rights lawyer, emerged from the same legal milieu. The legal sector generates 1.6% of GDP annually.
The rise of legal activism in Britain was enabled by the Human Rights Act, which opened practically all government action to challenge, and the spread of "no win, no fee" arrangements. Civil servants must read a guide titled "The Judge Over Your Shoulder" on how to avoid challenges from firms like Leigh Day. Both the Conservatives and Reform UK have pledged to withdraw Britain from the European Convention on Human Rights.
Hard reality has a way of cramping your style.