Centralisation is the process by which the activities of a business or organisation, especially planning and decision-making, are concentrated within a particular location and/or group, generally the head office. During the evolution of procurement there have been cyclical trends towards centralisation of procurement and then towards de-centralisation. Hybrid models have also emerged, such as federal or ‘CLAN’ structures. Centralisation can be effective in gaining control of the spend portfolio, helping promote consistent adoption of policy and procedures, allowing concentration of scarce procurement resources and offering a career progression for procurement practitioners. See also CLAN and Decentralisation.