Instead it's entirely below ground save for 15 measly seconds' travelling time. For someone charged with the self-appointed task of hopping on and off trains in order to pop in and out of every station, the prospect of almost a dozen round trips on soot-lined escalators via almost a dozen dirt-blown warm-to-baking platforms was not a welcome one. I thought the reason why there are so few lines running south of the Thames was because of the poor composition of the earth - yet here was a line remaining stubbornly out of daylight until almost journey's end.
In fact if you count the Northern Line's submersion between Morden and East Finchley as a continuous excavation, you have one of the longest tunnels in the world: 17.25 miles. I'm still picking the black snot out of my nose now.
Anyway, at least those near-dozen soot-lined escalators almost wholly conform to this brilliantly preserved art deco style of lighting:
And it'd be churlish to not admit some of the most strikingly-ornate stations of - I suspect - the entire network can be found south of Kennington, courtesy of Charles Holden who designed every single one of the class of 1926 (Clapham South - Morden inclusive). Indeed, as you head south from Kennington you move through four decades of history, beginning in the 1890s and ending up between the wars. So it's not all bad. Plus it even rained while I was doing this stretch, meaning at least I was cool above ground.
Both Oval and Stockwell originally hailed from 1890 when they formed part of the old City & South London Railway. Oval's interior has long been tastefully decked out in the inevitable cricket murals, while outside a nearby fountain afforded the chance for some ill-advised experimental photography.
Stockwell was opened in 1890 by the Prince of Wales, later King Edward VII, but has since been totally rebuilt - several times. Originally it was the terminus for the world's first ever deep-level underground line, the City and South London Railway, which ran from King William Street (near Monument). It's now an interchange with the Victoria Line. Interchanges, I'm learning, are never that nice to look at from the outside. Still, it's another of those stations with a deep-level World War Two air-raid shelter underneath - the fourth I've met so far on my journey (after Belsize Park, Camden Town and Goodge Street). There are three more further south on the Northern Line - Clapham North, Clapham Common and Clapham South - with the eighth, and only non-Northern Line shelter, buried at Chancery Lane.
Here's a photo of Clapham North, and I'd like you to observe closely the behaviour of its subjects.
Yup, that's right - everybody is talking into a mobile phone. It wasn't staged; I only noticed it when I got home. Until the technology arrives that allows people to use mobiles underground, I guess this kind of sight, persons clustered around station entrances like workers round a factory tannoy, will only compound itself.
Of much more excitement (relatively speaking, of course) is the fact that Clapham North shares with its neighbour Clapham Common the distinction of being the only two below ground stations on the entire network which have single island platforms, i.e:
It makes for a right scrum when trains arrives simultaneously, reminiscent of those dreadful scenes in the Forty Minutes documentary on Angel when a horde of passengers fight to go up and down the same set of stairs at the same time. Fortunately it wasn't rush hour here:
It's actually quite thrilling (again, relatively speaking) to use such a perfunctory, if perilous, platform. Above ground Clapham Common (built in 1900, like its predecessor), boasts an equally distinctive quality...
...no proper station building. This dome sits on a traffic island. I'm glad I caught the rain in this photo.
When you get to Clapham South you're at the first of Holden's buildings, all opened in 1926, all to a similar design, and all defiantly eye-catching. This one sits on the edge of the common (grass included in shot) and was originally going to be called by the far more evocative name of Nightingale Lane.
This photo of Balham was taken a year ago, when I was walking the Capital Ring.
Meanwhile back in 2007, Tooting Bec was bedecked with flowers.
And Tooting Broadway was blessed with a statue of his nibs Edward VII himself.
More of the same excellence at Colliers Wood:
South Wimbledon isn't even in Wimbledon, but was given its name in the belief that Wimbledon had a higher social standing than its actual location of Merton.
And so to the end of the line: Morden.
For so many people, both Londoners and tourists, Morden must only ever exist as a name on a loudspeaker, flatly declaring "this train terminates at Morden". As such it's easily better known than any of its near neighbours on the Northern Line, yet is probably the least visited. It's an incredible edifice, originally built by Holden on open farmland and intended to form part of a larger complex of local shops and businesses. Suffice to say you'd need to head a good deal further south than this - already the southernmost station on the entire Underground - to find farmland now.
Despite the unexpected quirks and unanticipated delights encountered on this first line of my tour, my attitude towards the Northern Line hasn't changed from the outset. It still frustrates me as much as inspires. Apparently the endless engineering work will ultimately result in a new signalling system allowing for, I think, an 18% faster service, whatever that means.
To be honest, I'd settle for one that runs the same speed it does now but is slightly cooler than the inside of an incensed potter's kiln.