A long-term natural ageing programme was started in 1958 when 19 rubber compounds were exposed at 3 locations. The final sets of test pieces were withdrawn in 1998 giving a total of 40 years of natural ageing. This report details the results of the artificial weathering and ozone exposure tests and makes comparisons with the results after natural ageing. The following properties were selected for monitoring the artificial weathering exposures; tensile strength, elongation at break, stress at 100% elongation, stress at 300% elongation and microhardness.