It was CGP 421S We've identified this vehicle using the details you provided FORD CORTINA L 1978 Registration number: CGP 421S Body type: 4 Door Saloon Colour: Blue Date of first registration: June 1978 .............. To rename then... Cortina L played in the same ep. -> /vehicle_1003696-Ford-Cortina-1977.html Maybe they borrowed plate's signs combination from it.
TS185, B or C model