The London Clay contains a rich, diverse, and historically important flora of Eocene age. However, until now fossil determination has relied on the use of several, separate, specialist monographs. This new guide uses keys accompanied by photographic illustrations to identify over 250 species including all of the common plant macrofossils. A more expanded text deals with those modern angiosperm families whose fruits and seeds are well represented in the London clay flora. The palaeoenvironmental implications of this flora are discussed and the ranges of the species are fitted into an up-to-date stratigraphical framework. Together with details of twenty-two localities in the London and Hampshire Basins, notes on collecting and conservation techniques will assist the collector, whether amateur or professional.