had a blue and green scheme. From May 1987 onwards, both HST and Mark 3 loco hauled sets were repainted and refurbished into the Intercity swallow livery. Previous formations Virgin CrossCountry proposed operating HST sets in shortened 2 power car and 5 trailer formations to be known as Challenger sets painted in the silver and red livery. This would give the trains better acceleration, similar to the Voyager units. Approval was not granted for this however. Current formations CrossCountry 9 (2 Powercars and 7 coaches), Following the May 2019 timetable change, GWR now run exclusively "Castle" sets formed of 4 coaches and 2 power cars. ScotRail have operated 4 coach sets with 2 power cars, on Scottish InterCity routes since 2018. Most ScotRail sets will be extended to 5 coaches. Hauled stock Mark 3A coaches were deployed on West Coast Main Line expresses out of Euston to bring the three main long-distance routes from London up to the same standard. Initial variants were Second Open (TSO) and First Open (FO). Catering and sleeper vehicles continued to be Mark 1 stock until the introduction of Restaurant Buffet (RUB) vehicles in 1979-80 and the sleeper (SLEP) vehicles in 1981–82. In 1988 the process was completed with the elimination of Mk 1 parcels vehicles and their replacement by Mk 3-derived Driving Van Trailers, making the WCML push-pull. Scottish Region push-pull services were initially made up of four TSO and one FO Mark 3A coaches with a Mark 2F DBSO. The FO was later converted to a Composite Open (CO) by the declassification of half a coach and installation of a partition between the two classes and an SO was removed. These vehicles were removed from the Scottish regional routes in 1989 when they were replaced with Class 158 multiple units. Chiltern Railways employs several rakes of Mark 3 carriages, hauled by Class 68 locomotives in push-pull configuration with Mark 3 Driving Van Trailers. These Mark 3 carriages have been extensively refurbished and modernised with the following enhancements: Application of new Chiltern Railways Silver Mainline livery based on the former, defunct Wrexham and Shropshire livery of two tone silver Automatic plug doors in place of the original slam doors (except for the two doors adjacent to the buffet car counter, which are no longer for public use) Large doorway vestibule areas Installation of economical controlled emission toilets with retention tanks Retrimmed carpets in new