One of the traditional activities of the National Physical Laboratory is its work on the maintenance and improvement of the primary standards of measurement. Although one may possibly visualise such work, because of its long history and its association with calibration services, as of a largely routine character, this is certainly far from the case at the present time. The present is a period of considerable activity and change in fundamental metrology, with the classical material standards of measurement being superseded by atomic or quantum standards. The past decade has seen a change to atomic standards for the units of length and time, and there seems little doubt that the future will see an extension of atomic-based standards to other areas, notably that of the electrical quantities. Some of the changes which may come about as a consequence of adopting the most accurate and convenient quantum methods have interesting implications. For example, a possible outcome of the new techniques being developed for the accurate measurement of very high (infrared) frequencies is that the standards of length and time may become unified, with the velocity of light taking the role of an agreed defined constant rather than an experimentally determinable quantity.