M@

London's Forgotten Tube Line

Have you ever caught the Northern City line?

That's right, the Northern City line. London's forgotten tube line still runs out of Moorgate, through Old Street, Essex Road, Highbury, Drayton Park and Finsbury Park, where it joins the East Coast Mainline to such exotic places as Hertford and the garden cities of Letchworth and Welwyn.

Unusually for a national rail route, the inner London stations are all deep underground. Below, for example, is Old Street. A soot-smeared sinusoidal subway leads to the platforms. It curves its grubby way around who-knows-what subterranean impediments.

Both the platforms and the trains are a 1970s throwback. This clearly looks like a tube stop, but with a garish livery that pairs bold blues and reds with a meek salmon background. The lower border sports a shade of green familiar to anyone who's ever regurgitated absinthe. It's like meeting a twin-brother of the tube, which was separated from its sibling four decades ago, and never quite moved on with the times.

Our train pulls in. They're every 10 minutes on weekdays — effectively a turn-up-and-go service like elsewhere on the underground. But these trains are too big for the rest of the deep-level tube. These are National Rail carriages, operated by Govia Thameslink. They are the oldest on the national network, and entered service in August 1976. Regular passengers may like to draw comparisons with the Muppet Show, which debuted a few days later.

Midday on a Tuesday, and our carriage is all but empty. It's a different story during rush hour, or when Arsenal are playing at home (Drayton Park). Although largely forgotten by the rest of London, the route is supremely useful if you work in the City and live in London's northern suburbs. You can be at Finsbury Park in 12 minutes. Moorgate to New Barnet is 10 minutes quicker than a similar journey (Moorgate to High Barnet) on the Northern line.

If the route shares similarities with a tube line, that's because it used to be one. Between 1904 and 1975, the line was a bone fide part of the London Underground. It appeared on the tube map under various guises, finally settling as the Northern line (Highbury Branch) before its handover to National Rail. Most people today call it the Northern City line, although its official designation is the Moorgate line. It's not on official tube maps these days, but still carries murky route posters in a similar vein.

Even if you've not heard of the Northern City line, you've probably encountered some of its history. The most serious accident on the London Underground occurred at the Moorgate terminus on 28 February 1975. A passenger train hurtled into the station without braking, hitting the dead-end wall at speed. 43 people were killed and many seriously injured. The circumstances behind the crash are still debated. Memorials can be found outside the station, and in nearby Finsbury Square.

Several extensions to the line were proposed, including a link-up to the Finsbury Park to Highgate railway. It never happened, but the latter route is preserved as the Parkland Walk, a linear green space that comes with its own tube-style map.

The trains still rumble on between Finsbury Park and Moorgate, but change is a-coming to this antiquated line. New carriages are on order. These babies should enter service in 2018. Thereafter, the Northern City line would be a likely target for Transport for London, which hopes to pull further suburban train lines under its control. If the tube map still exists in a decade's time, we might once again see the Northern City line snaking north between the Piccadilly and Victoria.