There were 29 four-coach Corridor sets (3101-3129) and 19 four-coach Restaurant sets (3054-3072 4-Res) units built for the 1937 Porstmouth electrification. For the Mid-Sussex electrification a further batch of 4-Cor units were built numbered 3130-3155 and 13 four coach units with buffet cars instead of Restuarant cars (3073-3085 classified 4-Buf) were built at Eastleigh. The Restaurant cars were withdrawn during the war and some became war losses which resulted in the coaches from 3058, 3060 & 3063 being reformed as 4-Cor units 3156-3158.The coaches for these units were all built at Eastleigh except for the 1st class Restaurant cars built by Metro-Cammell and the 2nd class Restaurant cars built by Birmingham C&W.

In 1961 three kitchen diners from 4-Res units 3056/65/68 were sent to Eastleigh where they were converted into griddle cars serving hot snacks. This entailed removing the complete interior and much of the exterior which resulted in a hybrid Maunsell/BR vehicle. At the same time the seat arrangement in the diner firsts of these units was altered from 12 chairs at 4 tables to 4 chairs at 2 tables with 8 loose chairs. The three units were classified 4-Gri but kept their original unit numbers until December 1963 when they were renumbered as 3086/87/88.

The route code was mounted in a box that was the other side of the gangway connection from the driver's window, thus giving them a "one-eyed" look, which led to them gaining the nick-name of "Nelsons".

With the introduction of 4-Big/Cig and 4-Vep units, these veterans were moved to stopping services around the Southern.

Following the introduction of the Cig and Big stock on the Brighton main line displaced 6-Pan units, N°3027, N°3031 and N°3033 were disbanded with some of their trailer seconds used with the remainder of the former 4-Res fleet to form seven 4-Cor(N) units. Unit N°3062 was renumbered N°3065 and N°3064 was renumbered N°3068, making up a consecutive series 3065-71