https://en.wikipedia.org/wiki/Partridge_v_Crittenden
Partridge v Crittenden [1968] 1 WLR 1204 is an English case, which was heard by the Divisional Court of the Queen's Bench Division of the High Court of England and Wales on appeal from the Magistrates' Court, and is well known (amongst other cases) for establishing the legal precedent in English contract law that advertisements are usually considered to be invitations to treat.