I understand that Ian Allan originally worked in the Public Relations department of the Southern Railway and it was due to the correspondence that he received from enthusiasts whilst there that led to the putting of the locomotive information together in one booklet and arranged for it to be published, hence the Southern Locomotives being the first ABC to be issued.  Following the obvious success of the first couple of issues he left the SR to work full time in publishing.

ABC of Southern Locomotives
Surprisingly the Ian Allan ABC's appeared during the middle of the Second World War with the very first issue being 'ABC of Southern Locomotives' in December 1942.  This was quickly followed by a second edition in February 1943.  These handy pocket sized booklets (6'' x 4'', approximately equivalent to today's A6) contained a complete listing of all locomotive numbers, and their classes split into Western, Eastern and Central sections.  Also included was a list of named engines, a table of principle dimensions, a list of the Southern Power Classifications, and dates of all the Locomotive Superintendents (Chief Mechanical Engineers) of the Southern Railway and its key constituents.

The 3rd Edition appeared in April 1943 and differed from the first two editions in that it was illustrated with black and white photographs of many of the engine classes.  These photographs were from either the Southern Railway itself or from the collections of well-known railway photographers such as O.J. Norris, A.B MacLeod and in later editions also E. Elsey and H.C. Casserley.  It was this issue that set the style and layout for all Ian Allan ABC's for many years to come.

1943 also saw the introduction of ABC's for the other 3 of the big four railway companies with the LMS 1st edition in June, GWR in October and the LNER November.

A complete list of ''ABC's of Southern Locomotives'' is as follows:

Following nationalisation and the renumbering the Southern Region locomotives were listed in the ABC of British Locomotives Part 2, Nos. 10000 to 39999.  I believe that they stayed in this format throughout the 1950's.  The infamous combine volumes were also introduced in the early 1950s.

ABC of Southern Electrics
Following popular demand Ian Allan issued the first ABC of Southern Electrics in October 1943, which as well as the usual listing of set numbers and illustrations it included information of formations with nice formation / interior diagrams, a diagram of routes covered by electric units and also a complete listing of EMU headcodes.

Commencing with the 5th Edition in January 1946 the booklets became ABC of Southern and LMS Electrics.  As stated above the 6th Edition in April 1946 still retaining the LMS Electrics was sold in a combined issue with the 9th Edition of Southern Locomotives.

A complete list of ''ABC's of Southern Electrics'' is as follows:

January 1948 saw the introduction of the booklet ABC of British Electric Trains covering all regions and the few independent electric trains such as Manx electric railway and the Swansea and Mumbles railway.  A further unnumbered edition of Southern Electrics was published in 1949.

ABC's in the 1950's

Following nationalisation the ABC's were published in a number of parts. Part one covered numbers from 1 to 9999, Part 3 covered numbers from 40000 to 59999 and part 4 covered numbers 60000 to 90999.

Part 2 included all numbers from 10000 to 39999, which therefore meant as well as all Southern built locomotives it included all diesel electric and diesel mechanical locomotives.  This means that until the Summer 1957 edition, spotters on the Southern region would also require other parts for the BR standard and Austerity locomotives allocated to the Southern Region.  These publications continued to include a list of the Southern Head Signals.

Publication dates in the 1950's, known to the writer, were as follows:

• January 1949: details correct to 31st October 1948.  This edition also includes a table of the new motive # power classification codes such as 7P & 6MT.
• Spring 1950: details correct to 4th February 1950.  Includes the five Leader class numbers.
• February 1951: uniquely this issue also included shed allocations. In future the shed allocations were included in a separate Locoshed range of publications.
• May 1951: no actual date included.  Chapter detailing the new proposed standard classes included.
• Summer 1953 edition: published in May 1955; details correct to 27th March 1953.  This issue also included a listing of Southern Electric Motor Units.  Leader Class no longer included.
• Summer 1954 edition: published in June 1954; details correct to 13th May 1954.  From this edition a listing of Pullman Cars allocated to the Southern Region was included.
• Winter 1954/5: published in October 1954; not in my collection.
• Summer 1955 edition: published in May 1955; details correct to 20th April 1955.
• Winter 1955/6 edition: pubished in September 1955; details correct to 12th August 1955.
• Summer 1956 edition: published in April 1956; details correct to 20th April 1956.
• Summer 1957 edition: published in April 1957; details correct to 1st April 1957.  From this issue the list of Southern Electric Motor units and the Pullman car list were omitted but a listing on BR standard classes and WD Austerity numbered from 70000 to 99999 was included.
• Winter 1957/8 edition: published in September 1957.  Includes a useful table on BR Standard tender types and to which locomotives they are allocated.
• Summer 1958 edition: not in my collection.
• Winter 1958/9 edition: published in October 1958.
• Winter 1959/60 edition: published in November 1960.
• Summer 1960 edition: not in my collection.  Following this publication Southern and Western Region locomotives number were combined in one volume and the increasing number of Diesel and electric locomotives given their own volume.