To provide the service the coaching stock consisted of eight electrically powered multiple units each made up of three coaches, which were built by the Metropolitan Amalgamated Railway Carriage and Wagon Company.

CP Stock

photograph: O J Morris

A four car train complete with electric bogie power van at Coulsdon North in July 1928

Apart from the pioneer South London units (See the pages on 2SL and 2Wim units) two designs of electric units were inherited by the Southern Railway from the London Brighton and South Coast Railway which were to be absorbed into the general suburban fleet.

Following the success of the "Elevated Electric" scheme, the LBSCR embarked on further extensions the their 6,700 volt system and opened further lines from Victoria and London Bridge to Crystal Palace via Streatham Hill on the 1st of June 1911 and from Battersea Park to Crystal Palace Low Level and on to Norwood Junction, with the Peckham Rye - Dulwich - West Norwood line which were brought into use in 1912.

The new trains for these services were made up of thirty-four motor brake third class coaches and seventy driving trailer composites. The Crystal Palace tunnel was particularly narrow and as a result this stock was only 8ft 0ins wide. The trains were classified "CP" and, although the formation of trains varied, generally, but by no means exclusively, they consisted of a driving trailer either side of one of the motor brake thirds with two such configurations coupled together at the rush hour. Building of the new units was split between the Metropolitan Carriage and Wagon Co who built the motor coaches and 34 of the driving trailers and the LBSCR's coach works at Lancing in Sussex which built the remaining 36 trailers.

CW Stock

photograph: British Railways

One of the bogie power vans - commonly referred to as "Milk Vans" - used on the Coulsdon North and Sutton electrification.

Since most of the electrical equipment originated from AEG in Germany further extensions to the overhead system were brought to an abrupt halt by by the First World War. Nevertheless in the run up to the grouping in 1922 it was agreed by the constituent companies that the overhead system should be extended. As a result even before the grouping, further extensions were put in hand to the overhead system from Balham through East Croydon to Coulsdon North and also from Norwood Junction through West Croydon to Wallington and Sutton. These were completed in 1925.

The stock for these sections was built after the grouping mainly at Lancing but with some coming from the former LSWR works at Eastleigh and some from the Metropolitan Carriage and Wagon Company. It consisted of sixty driving trailers and twenty intermediate trailers. Traction power was provided by twenty-one driving motor vans which were generally referred to as "milk vans". A 250hp traction motor drove each axle of both bogies of the motor van, they had a cab at each end and in addition they also had the guard's brake and luggage space. With a view to conforming to the current European standard the "milk vans" were designed to allow them to be converted to 11,000 volts.

Varying numbers of trailers and driving trailers were coupled to either end of the motor van to make up trains of the required length. This was known as the "CW" stock.