When Dr Campbell Smith published and compiled his first account and catalogue of British jade implements he did not think, he tells us, that many more would be found. For this reason he adopted a numbering system based on counties, as is done for all other stone implements, but with numbers running consecutively through the English, Scottish and Irish counties. When new finds came to light it was difficult to assign to them numbers in the county system and the problem was resolved by numbering them 17b, 32a etc. New discoveries of jade implements are being made at an accelerating rate. In Campbell Smith's Second Supplement (1972) he records nine new finds during the previous six years, but since 1972 we have become aware of a further 24 implements. Partly because of this, and partly as a result of typological and mineralogical studies we have been making, it seemed to us that it would be useful to bring the catalogue up to date, whilst at the same time taking the opportunity of simplifying the numbering system. Although still taking a very positive interest Dr Campbell Smith is no longer actively engaged in work on jade implements. However, for the sake of continuity it was deemed useful to call this report the ‘Third Supplement’ even though the present authors were not involved with Dr Campbell Smith's original Catalogue and Supplements.