expensive in comparison with the safety benefits. In October 2002 the Health and Safety Executive extended the permitted use of Mark 1 based rolling stock until 31 December 2004 with the proviso they be fitted with a Train Protection & Warning System. Post-privatisation During the 1990s, the few remaining Mark 1 loco-hauled vehicles on the main line were withdrawn, having been progressively replaced by Mark 2 and Mark 3 stock through the 1970s and 1980s. However, the extensive Network SouthEast commuter network on the former Southern Region operated by the Network SouthCentral, Network SouthEastern and South West Trains shadow franchises was worked mainly by Mark 1 based multiple units of the 205, 207, 411, 412, 421, 422 and 423 classes. When British Rail was privatised in the mid-1990s, only Connex South Eastern was given an extended franchise (15 years) in return for ordering new trains. Connex South Central and South West Trains, the other major users of Mark 1 multiple units, were not required to order new trains. As a result, in 2000, Mark 1 units were still in use across most of the former Southern Region with no new trains having been ordered. When the franchises were relet in the early 2000s, they were done with a requirement to replace the Mark 1s, thus hundreds of new multiple units of classes 171, 375, 376, 377, 444, 450 and 458 were introduced by Connex South Eastern, South West Trains and Southern between 2001 and 2005. A similar story took place in Scotland, with the last of ScotRail's Mark 1 based Class 303 multiple units surviving until December 2002. The use of Mark 1 stock on postal trains was curtailed when the Royal Mail partially replaced them in the early 1990s. The postal train services on the West Coast Main Line were worked using new Class 325 multiple units. However, these units proved to be extremely troublesome in service and due to technical failures were often loco-hauled instead of running under their own power , and therefore Mark 1 formations continued to be used here, and elsewhere on the network. However, in January 2004, the Royal Mail ceased using rail to transport mail traffic. Thus, the problem of how to replace the large numbers of Mark 1 carriages on these services was resolved. Network Rail continue to use converted Mark 1 coaches for various departmental duties – test trains, sandite units,