I’ve consulted a number of books in order to get the history of the time and the area about right. In particular, I would like to acknowledge the following works:
London’s Lost Route to Basingstoke: The Story of the Basingstoke Canal, by P. A. L. Vine, published by Allan Sutton Publishing, 1968 (revised and expanded in 1994) — great material about the local waterways and canals in the Farnham area.
The Tongham Railway by Peter A. Harding, self-published 1994 — obviously the product of one man’s obsession, but immensely useful.
Bygone Farnham by Jean Parratt, published by Phillimore & Co. Ltd, 1985. Useful if only for the exhaustive list of pubs and taverns it contains, which suggests that every second house in Farnham sold beer.
London Under London — A Subterranean Guide by Richard Trench and Ellis Hillman, published by John Murray (the original publisher of the Sherlock Holmes stories in book form), 1984. The classic guide to London’s underground rivers and tunnels.
Subterranean City — Beneath the Streets of London by Antony Clayton, published by Historical Publications, 2000. Covers much the same ground (as it were) as Trench and Hillman’s book, but benefits from material more recently discovered. Or perhaps “unearthed’ would be a better word.
The London of Sherlock Holmes by Michael Harrison, published by David & Charles, 1972. An invaluable and immaculately researched investigation of what London would have looked like to the eyes of Sherlock Holmes.