Experience outside the UK with service failures of wet MV extruded dielectric cables has led to extensive worldwide studies. This article describes work carried out at BICCGeneral UK since the 1970s and reviews the results of long-term tests (up to ten years) under working conditions on cables manufactured ipl the 1970s and 1980s. The results ave compared with data from two-year UNIPEDE tests at 2.5U(0) on 1990s cable and demonstrate the goon service performance obtained with these cables. European and North American service failure data, obtained from the literature, is then used with the service survival data on these cables to estimate their expected lifetime.