The Gold Medal of the Institute of Mathematics and its Applications (IMA) is a biennial prize established in 1982 by the IMA "in recognition of outstanding contributions to mathematics and its applications over a period of years".
These contributions may take several different forms, including "the building up of a research group of exceptional merit", "notable contributions to the application of mathematical techniques" or "outstanding contributions to the improvement of the teaching of mathematics".
[1][2] Source: Institute of Mathematics and its Applications