The paper discusses a number of practical case studies of operational research in the UK coal mining industry and relates the effectiveness of the work to the principles which underlie the organisation and control of the OR team. The first part of the paper discusses the way in which the service to local management is supported by the work of the Headquarters sponsored research teams and illustrates this with a list of the achievements of one such local team in the course of a year. The second part of the paper discusses some case studies in mine planning and the techniques that have been developed to handle some recurrent problems. The final section discusses the use of interactive modelling for planning purposes at unit and Headquarters level in the Board's coal products organisation. The paper concludes with a brief discussion of the relative value of optimising and interactive models.