I'll confess: I am a bit of a trainspotter. Just a little bit, mind. I am particularly infatuated with London Underground. I can't really explain just why I find the system so fascinating - perhaps it's because it seems both so modern and so antiquated, always on the verge of total collapse. To feed my obsession, Marcus bought me a brilliant book: Mind The Gap by Simon James.



Intrigued by those faraway-sounding, almost mythical, placenames in Tube tannoy announcements ["this train is for Hainault via Newbury Park"], James bought himself an all-zones Travelcard and photographed the stations at the ends of the tube lines. Surprisingly, some of these stations are not the tatty suburban backwaters you might expect. I am going to have to invent a reasons to go to Hillingdon and Cockfosters just so I can gawp at the architecture of their stations. And I simply have to see the Secret Nuclear Bunker at Ongar.

The book is littered with the kinds of trivial facts that turn me on:

The Metropolitan Railway - the world's first underground railway - opened between Paddington and Farringdon in 1863.

Until electrification in - wait for it - 1962, the Chesham and Amersham brances were powered by steam.

The Victoria Line is the only true "tube" line, submerged for the whole of its 22 kilometres.

Greenford is the only place on the network where you need to take an escalator up to the Underground.

The longest continuous journey on the Underground [excluding going round and round on the Circle] is the 54 kilometres from West Ruislip to Epping.

Watkin's Folly was begun in 1889, and was to be a tower which would dwarf the Eiffel Tower. Due to lack of funds and public indifference, it was never completed. A similar fate appears to await the structure which currently stands on this spot - Wembley Stadium.

Aldwych tube station closed down in 1994. The reason? Passenger numbers were not sufficient to justify spending the more than £3 million required to refurbish the lifts.

Amersham Underground station is the network's highest, at 150 metres above sea level.

Hampstead is the deepest below street level, at 58.5 metres. The deepest point below sea level occurs on the northern line, just south of Waterloo, at 21.3 metres.

The longest distance between two stations is 6.26 kms - from Chalfont & Latimer to Chesham on the Metropolitan.

The shortest distance is between Leicester Square and Covent Garden on the Piccadilly Line - just 250 metres.

The Circle Line platforms at Aldgate are the only platforms on the network that belong exclusively to the Circle Line.

At full capacity, an eight-carriage Central Line train will carry 1,652 passengers through tunnels four metres wide.

Loads more facts and figures can be found on this page. I'll get me anorak.