Somehow, those fascinated by London's Underground have escaped the stigma of trainspotters. In fact the Tube is almost cool.
Perhaps it's Harry Beck's schematic map, or the easily recognisable design of many stations: Leslie Green's turn-of-the-century tiled facades; Charles Holden's polite Modernism in the 1920s and '30s; or the Jubilee Line extension, which resembles nothing so much as a Ken Adams film set.
Whatever the reason for Tubespotting's unlikely chic, two unabashed enthusiasts (in association with the London Transport Museum) have published works on their pet subject; but they approach the Underground's history from utterly opposite standpoints.
In The Moving Metropolis, Sheila Taylor venerates progress, presenting an epic history of London's transport from 1800 to 2000 - its evolution from the first electric subway in 1901 to the disaster-in-waiting we ride today. The much slimmer London's Disused Underground Stations, conversely, questions the price of too-rapid progress. Author J E Connor lovingly lists buildings and even entire spur lines suffering premature redundancy; forcibly abandoned through the Tube's uneven expansion and usage, sometimes bang in the middle of the city. Real estate worth huge sums in theory, but often, in practice, unable to be sold off.
Taylor's well-organised work begins at a time when London used the Thames as its main artery, by means of wherries (rowed water taxis), moving swiftly on to the advent of steam railways. 'By the 1850s, ' she writes, 'it often took longer to cross central London than to travel up to the capital by train from Brighton.' (Nothing new there, then. ) She covers both wars and the rise of the automobile, finishing up with a flourish and the new Jubilee Line stations. The end of each chapter is lavishly illustrated with photographs, maps, posters and logos, and the book has been extensively indexed.
J E Connor's subject is no less fascinating, showing how, over time, the way Londoners flow through their city changes enormously, sometimes in less than a decade. Hounslow Town station, for instance, opened in 1883 and temporarily closed in 1886, reopened in 1903 only to be permanently shut in 1909.
Followers of the current debate over the Tube's future may find these historical uncertainties illuminating.
Unfortunately Connor has organised the book rather unhelpfully - chronologically by date of final closure (or resiting) of each station - and the alphabetical list of closed stations on the very last page contains no page references.
Like Taylor's book, Disused is liberally strewn with maps, photos, diagrams, even newspaper cuttings, such as a letter to the editor of The Times complaining about poor Tube service, dated 1933. Each station closure gets a 'potted history', but as a whole the book lacks coherence and analysis.
Nowhere does Connor give an overview; he draws no generalisations from various closures, nor does he mention why he has included only 21 out of more than 80 closed stations (and a few extras in the 'Minor Resitings' chapter).
Most importantly, although he alludes to it in his final chapter, 'Disused Street Level Buildings', Connor never explains the Tube's unitary ventilation system, which dictates that no disused station can be simply demolished or sealed over.
Both books are informative enough to reward the true obsessive, but both, too, are excessively sombre and reverential in tone - sometimes turgidly so.
Liz Bailey writes on transport and technology.
See the coverage of current transport trends in this week's issue (pages 38-42)