One of the key elements of this was the extension of Three Bridges to Bognor Regis stopping services to start and terminate at London Victoria. These trains would run through a reversible platform at Gatwick Airport where a portion would detach and wait in the platform for passengers until the next up train from Bognor Regis was attached and the train would depart for Victoria. For this service British Rail used a small batch of seven Class 402 "2HAL"s in order to work with the trains used on the Bognor Regis services, suitable for airport link use because of their larger luggage space.
This situation lasted until the early 1970s, when increased passenger and luggage travel to the station was rendering the old system obsolete, and the ancient Southern Railway-built trains were definitely showing their age.
In 1978 twelve Class 423 units, nos. 7788-7799, were fitted with extra luggage racks (by removing the squabs and backs from certain seats, reducing standard class capacity) and reclassified as Class 427 4VEG (VEP Gatwick Express) units. The units were renumbered into the range 7901-7912.
Externally these units wore British Rail Blue Grey livery, which was the standard until sectorisation, with "Rapid City Link Gatwick - London" lettering on the side of each driving vehicle. The British Rail logo and a generic aeroplane symbol were also on the side, identifying it immediately as an airport train.
The service however remained much the same, with the units attaching and detaching from Bognor Regis bound services running via Redhill. This led to somewhat extended journey times which meant the service lacked any real purpose, as the faster services began calling at Gatwick Airport from the early 1970s, and made the option of travelling to Gatwick Airport from London on the service lack appeal to those who knew better.
In 1984, the dedicated InterCity Gatwick Express began service, using modified Class 73s and Mark 2 coaches. The Class 427s were modified back and renumbered into their original set.