This paper examines methodologies for the simulation of storms for the purpose of design flood generation in the Thames region. Existing methods are reviewed and two new approaches are proposed. One combines point profiles of storms extracted from long rainfall records with depth-duration-frequency statistics. The other uses a stochastic rainfall model based upon the Poisson point process to generate data. Rainfall events simulated by these two methods are compared and the flood statistics obtained by inputting these events into a rainfall-runoff model are examined for a small catchment in Surrey, England. The Poisson based model is recommended as the more reliable.