s 18 Articles of association
(1) A company must have articles of association prescribing regulations for the company. (2) Unless it is a company to which model articles apply by virtue of section 20 (default application of model articles in case of limited company), it must register articles of association. (3) Articles of association registered by a company must— (a) be contained in a single document, and (b) be divided into paragraphs numbered consecutively. (4) References in the Companies Acts to a company's “articles” are to its articles of association.