For a very readable (and definitely non-trainspotter) history of the railways in Britain, see Fire & Steam by Christian Wolmar, (Atlantic Books), which I drew on widely in creating these pages. I also drew on his sequel, Blood, Iron & Gold, which is a history of the railways globally, and Eleven Minutes Late, by Financial Times journalist Matthew Engel (published by Macmillan) – a very readable reflection on the history of Britain’s railways and their place in our culture.
A more South East-focused version of the above is Kent Railways: The Age of Steam by David Staines (published by Countryside Books), which is a readable and interesting look at social and economic impact of the railways in the county.
Even more valuable if you can find a copy (it is out of print) is A Regional History of the Railways of Great Britain: Volume 2 - Southern England by HP White. My volume was published in 1961 and presents a bewitching picture of the South East's railways before the Beeching Cuts, as well as being full of historical detail. Forgotten Railways: Volume 6: South East England, written in the 1970s, is equally compelling but covers fewer, more obscure lines.
Of the trainspotter-type books, the most invaluable is the British Railways Pre-Grouping Atlas and Gazette (Ian Allan Publishing), which shows you every line, station and railway company that existed at the height of the railways in 1922.
Ian Allan Publishing also publishes a series of Lost Lines books by Nigel Welbourn. Lost Lines, Southern is the one most relevant to the lines we use as walkers, though Lost Lines, London also helped inform these pages.
More for the enthusiast, but invaluable in my researches were Railways of Britain: Kent and Sussex and Railways of Britain: London North of the Thames, both by Collin and David McCarthy (and both Ian Allan Publishing). These books detail every railway company that ever existed in their respective regions, and what happened to them.
If you want to wallow in nostalgia for a golden age that never was, the delightful South for Sunshine (Tony Hillmam and Beverley Cole: published by Capital Transport) is a small picture book of publicity posters of the Southern Railway, with images that make Seaford look as glamorous as St Tropez. Meanwhile, Paul Atterbury, published by David & Charles, has produced a series of coffee-table books on rural branch lines, including Branch Line Britain, On Country Lines and Tickets Please.
Of the many steam train photo books, one that is particularly relevant to the south east, showing many lines now closed, and which has photographs in colour to boot, is Southern Counties Branch Line Steam by Michael Welch, published by Capital Transport.
The bookshop of the London Transport Museum is a good place to find all the above
Some other historical books that I also drew on:
The Victorian Railway, Jack Simmons, Thames & Hudson – a seminal academic work on this subject, though probably too detailed for the casual reader.
The Smell of the Continent, Richard Mullen & James Munsen, Pan Macmillan, p157-162 - a charming account of how modern tourism was developed by Victorian travellers to Europe
Victorian London, Liza Picard, Orion Books, maps, p42-45, index p390 – an interesting anecdotal look at all aspects of Victorian life.
The Middle Class: A History, Lawrence James, Abacus, p368ff.
For the early history of the Metropolitan Line, the histories of the London termini, and for the page on the London's Victorian railways, the following books were also invaluable:
The Subterranean Railway, Christian Wolmar, Atlantic Books
The excellent but out of print London Railway History by HP White, Volume 3 of A Regional History of the Railways of Great Britain.
Discovering London Railway Stations by Oliver Green, published by Shire Publications in association with the London Transport Museum, which gives a short history of each of the London terminus stations.
London's Great Railway Century 1850-1950 by Keith Scholey, published by the History Press, a book which is full of fascinating detail on such topics as London's railway hotels and early electrification.
The London Railway Atlas published by Ian Allan Publishing: it shows every line and every station that ever was in the city, with dates of opening and closing.