
Is there a difference between 'the tube' and 'the underground'?
Yes, and no. Today, the two terms are used interchangeably by most people. But that wasn't always the case.
The older lines, such as the Circle, District and Metropolitan, run through large tunnels, with relatively roomy trains. These lines were constructed by 'cut and cover' — in other words, a huge trench was gouged out of the earth, and then covered over. Hence, they're just below the surface, and are often covered by roads, such as Euston Road or Embankment. From the opening of the first line in 1863, the system was generally known as the London Underground Railway, or the Underground for short. (Pedantic sidenote: it's often said that William Gladstone was among the first to ride through the tunnels, as shown in the picture below. He wasn't.)

By contrast, the rest of the network runs through narrower, deep-level tunnels, which were bored rather than scooped. The first, what we now call the Northern line between Stockwell and Borough, opened in 1890. These tunnels were quickly dubbed 'tube railways' because of their circular profile. The Central line, opening in 1900, was nicknamed the 'Tuppenny Tube', thanks to its fare price.
For the first few decades of the 20th century, a clear distinction was made between the two types of tunnel. Newspapers talk of the 'underground and tube railways', as though they were separate systems. And they were separate systems, with different lines operated by different companies. The system finally came together (mostly) as a unified whole in 1933, with the formation of London Transport.
After this merger, and the publication of the first modern tube maps, passengers began to think of the underground tunnels as part of one, coherent network. The difference between 'tube' lines and 'underground' lines has since blurred, and only the most pedantic, point-scoring person will maintain the distinction. TfL itself concedes that the Tube is 'an acceptable colloquial shorthand for the London Underground'.
Should I write 'tube' with a capital letter?
Transport for London tends to capitalise the word 'Tube' in all instances. Some publications, such as The Times, follow suit, and this is also preferred in the BBC style guide. Many other publications (including Londonist and the Guardian) use lower case. A third way is to use upper case when talking about the Tube (as in, the whole network), while using lower case for its more generic attributes, like 'a tube line' or 'a tube station'. It's similar to how some writers will capitalise 'the Internet' or 'the Universe', bestowing the status of a proper noun on these systems.
King's Cross or Kings Cross? Earl's Court or Earls Court?
Apostrophes hold an endless fascination for the pedant. They're used with some inconsistency across the transport network, and we've had plenty of fun picking this apart before. You'll find a more detailed discussion on the link, but suffice it to say that both King's Cross and Earl's Court do carry apostrophes (at least on the tube map — Earls Court usually drops its punctuation elsewhere), while Queens Road (Peckham) and Barons Court do not.
Is the Elizabeth line classified as a tube line?
Despite appearing on the tube map, being deep underground and functioning much like a tube through its central sections, the Elizabeth line is *not* considered to be a tube line. It uses different rolling stock and livery (note the purple roundel versus the tube's red roundel).
So if it's not part of the tube, why is the Elizabeth line on the tube map? What is both colloquially and officially known as the tube map (or Tube map) contains much more than tube lines. It's a way of visualising the services owned by TfL, and also includes the Docklands Light Railway, cable car, various Overground lines and, the tram system.
It would be wrong to say the tube map shows all TfL services, however. The true pedant could point out that buses and cycle hire, for example, are not reflected on the map (with good reason). Nor would it be entirely correct to say that the map shows only TfL services. The diagram includes interchange symbols for mainline rail stations, Heathrow airport and Thames Clippers, not owned or operated by TfL — although the information is limited. Since 2020, it has also included the Thameslink service, which runs through central London, even though this is not a TfL line.
Can I still refer to the East London line?
For decades, the East London line ran from New Cross to Shoreditch. It closed in 2007, got stretched up to Dalston, then reopened in 2010. Many people still refer to the route as the East London Line. TfL does not. Not officially anyhow. According to its editorial style guide:
'East London line' is now 'Overground Dalston/Highbury & Islington - West Croydon/Crystal Palace/New Cross'.
Which is, of course, utterly ludicrous, quite possibly the longest name for a railway in the world, and surely the only line to have more forward slashes than a typical internet address. It even boasts more characters than the famously verbose Welsh station of Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch.
Even TfL rarely uses the official name in public communications. Tannoy announcements refer, for example, to 'the Overground to New Cross Gate', rather than the laborious technical name.
In case you're wondering, other parts of the Overground network have similarly tortuous official names:
- 'North London line' is now 'Overground Richmond/Clapham Junction - Stratford'
- 'West London line' is now 'Overground Willesden Junction - Clapham Junction'
- 'DC line/Watford Euston DC' is now 'Overground Watford Junction - Euston'
- 'Gospel Oak to Barking (GOB)' is now 'Overground Gospel Oak - Barking'
So, in answer to the original question: yes, use the East London line. Use the North London line. And most especially use 'the GOBLIN' to refer to the Gospel Oak to Barking LINe.
When does the tube end and the night tube begin?
Diamond Geezer has this one covered, with a nitpicky look at TfL's timetables. In summary: it's complicated.
Got any other pedantic questions about the tube? Ask below, and we'll see if we can find an answer.