Merger control in the United Kingdom has recently entered a new phase in its development. The advent of the relevant aspects of the Enterprise Act 2002 has been welcomed as a "depoliticisation" of the regime. The role of the Secretary of State has been all but excised, and the substantive criteria against which mergers are assessed have been revised to offer formally a competition-based standard. Together with guidance published subsequently, the reforms also prescribe a range of new procedural guarantees for those parties affected under the regime. In addition, the EC merger control regime and in particular the nature of its relationship with the competent authorities of the Member States has been significantly revised.It is against this backdrop that the authors--leading experts with first rate regulatory, practical and academic experience--offer a comprehensive statement of the law, architecture, and procedure of merger control in the United Kingdom; explain the factors pertinent to the economic appraisal of mergers in a manner accessible to a legal audience; and give invaluable practical guidance on managing the transactional process and regulatory risk.