In Parkin v Thorold (1852) 16 Beav 59, Lord Romilly MR held that "Courts of Equity make a distinction in all cases between that which is matter of substance and that which is matter of form; and if it find that by insisting on the form, the substance will be defeated, it holds it to be inequitable to allow a person to insist on such form, and thereby defeat the substance" (at pp 66-67). The distinction between form and substance is long-standing and is familiar to both Chancery and Common Law judges. In contract law, Bingham LJ (as he then was) had warned in Interfoto Picture Library Ltd v Stiletto Visual Programmes Ltd [1989] QB 433 (CA) that a court must be alive in identifying a "disguised penalty clause" which would be unenforceable at common law (at 439). With the apparent obsession of 'substance over form', does 'form' still have a role to play in private law? The collection of essays in this volume explores the interactions and influences of both camps within the law of obligations. Broadly speaking, the essays can be sorted into three clusters.