No wonder this is one of the busiest parts of the whole network. No wonder it's better to walk overground between most of these stations rather than put yourself through a few minutes of crush-carriage hell. No wonder these stations not only feel but most definitely look a century old.
One that I forgot to mention last time, and which isn't quite so busy - mainly because it doesn't exist anymore - is Aldwych. It's not been closed that long, comparatively; it shut in 1994 after ever decreasing usage and ever increasing costs. It was a route to nowhere, forming one end of a stub of a branch line that spewed off north of Covent Garden. Originally it was to be the southern terminus of the Great Northern and Strand Railway, running from Finsbury Park in the north, under King's Cross station, to a point near The Strand. But the concoction of the Piccadilly Line put pay to all that.
I'm not sure I miss it that much. It always looked out of place on the Underground map. It didn't fit into the logic of Harry Beck's original diagram, appearing squat and ugly. It didn't seem sensible to have a branch line going nowhere right in the middle of London. It didn't even serve a part of the city barren with Underground stations.
Still, it's one of the most easily located disused stations in the city, bearing its original name 'Strand'. And it's always turning up on TV and in films, whenever 'Generic Underground Station' is required, so it's not entirely redundant.
South of Covent Garden and Leicester Square, where I've been before...
...is Piccadilly Circus: a swaggering ogre of a station, none of which lies above ground, but which rolls majestically in a giant circle just under the titular thoroughfare.
The cavernous complex is a fantastic creation, unsurprisingly the work of Charles Holden (though the old, above ground booking hall, closed in 1929, was Leslie Green's handiwork), around which flock folk from all corners of the globe, defiantly pushing train tickets into incorrect slots, filming everything on camcorders, and shouting. It's a mini-tornado down there. I've never been inside the station and not felt half-swept up by a torrent of bodies bobbing and weaving non-stop around and around and around.
Beyond Green Park, another old friend, of which there will only be more as this project continues...
...lurks another disused station, but with nowhere near the pedigree of Aldwych. Down Street was axed in 1932, briefly sparking back to life during the Second World War when Churchill and his War Cabinet used it as an air-raid shelter. It seems to have been something of a folly from the start, though, as it was built in an area (Mayfair) where the residents were too posh to want to use the Underground and just that bit too close to its neighbouring stops.
The surface building, another Leslie Green creation, is still standing, albeit shorn of its original purpose. Just like that of its neighbour, Hyde Park Corner:
Green's entrance hall is now a pizza restaurant. This station is, boringly, entirely below ground.
As you'd expected, entering and existing Knightsbridge is a right roustabout. Especially the entrance right next to Harrods.
All the stations on this stretch of the line were opened almost exactly 100 years ago. There's little of the original Knightsbridge nowadays, thanks to an apprently unending attempt to render it more fit for coping with batteries of consumers charging for bargains.
The tunnels between Knightsbridge and South Kensington allegedly follow such a twisting route to avoid a 17th Century plague pit. Lurking in their depths is yet another ghost station: Brompton Road. Despite proving convenient for the eponymous Oratory and the Victoria and Albert Museum, it was pretty much ignored once Knightsbridge station started expanding, and was duly boarded up in 1934.
So to South Kensington, where the Piccadilly aligns itself with one of the oldest Underground routes in the capital (the District), duplicating and stealing stops from this and other lines all the way out to Ealing and beyond. There's been a station here since 1868, the Piccadilly arriving in 1906 in its initial guise as the Great Northern, Piccadilly & Brompton Railway running between Finsbury Park and Hammersmith.
The new platforms needed a new building, which meant the existing, dazzling entrance...
...had a bit of Leslie Green ruby brick artistry bunged on the back.
As nice as South Kensington is, there's a huge case to be made for having a new station in this part of London, one that would mean you wouldn't have to walk miles through dripping, gloomy passages to get anywhere near to the Royal Albert Hall, the Royal College of Music, Hyde Park and Kensington Palace. It could be called Kensington Gore, or even just Albert Hall. Anyone standing for Mayor who put this in their manifesto would romp home.