In 1975, in his WMO GARP publication on the physical basis of climate and climate modelling, Ed Lorenz wrote: "I believe that the ultimate climatic models..will be stochastic, ie random numbers will appear somewhere in the time derivatives." Only recently has the world of weather and climate prediction begun to explore the use of stochastic representations of sub-grid processes.Recent work on the generalisation of parametrisation in Earth-system models to include stochastic-dynamic representations of the sub-gridscale world, will be reviewed. Attention will be focussed on the use of stochastic parametrisation to represent model uncertainty, and as a means for reducing model systematic error.