Home Tech Free WiFi: The mysterious affair on the London Tube

Free WiFi: The mysterious affair on the London Tube


This morning I descended into the deep depths of London's Piccadilly Line, settled into my seat and powered up the iPhone to continue reading the latest blockbuster. Normal day.

Suddenly I noticed a full set of wifi bars at the top of the screen. This couldn't be, I thought, as I swiftly called up Settings for a sitrep. Sure enough, I was connected to "Free Public WiFi" with a strong signal. 

For all of 30 seconds I was delighted until I realised that this munificent signal carried no internet connection.

Throughout the journey under central London the signal rose and fell, sometimes one bar, sometimes four. And still no internet. 

What gives? I honestly don't know and a trawl of the net brought no information. Some underground railways in the world do offer access to 3G cellular networks, but free public wifi? And I've heard no rumours from London.

This remains a complete mystery. Could it be some experiment on the tube system? Because of the depth underground – the Piccadilly line is one of the deepest – there is no chance of a stray signal from above (except from far above, in which case we could consider divine intervention). 

No, despite all my instincts against the verdict, this must be some fault with the iPhone. Anyone have any suggestions?

UPDATE: Our correspondent in Washington DC, who is a noted train buff, suggests that this mysterious signal could be testing for part of what London Mayor Boris Johnson has termed city-wide wifi before the 2012 Olympic Games. However, we can find no specific references to wifi on the Underground and any inside information would be welcome.

Blog posted here.


  1. Like you, I am at a loss to explain such a phenomena (um?) However, it sounds remarkably like the situation I have with my internet connection at home, if I am late with my monthly payment, I still have a signal, and can go on line, but can’t access the internet, if you see what I mean?

    Perhaps London Transport has a tribe of troglodytes (who perhaps look after the track between stations), and they have simply not paid this month’s internet dues?

    Or alternatively, here is a suggestion that would appeal to all you conspiracy theorists out there, what you were getting was the carrier wave for an ultra-secret London Transport Police communication system, based along the tracks of the Piccadilly line, whose job it is to listen into everyone’s mobile phone calls,and monitor anyone attempting to visit dubious websites whilst on their trains?

  2. City wide WiFi? Unsecured as well? Haven’t they been following the legal problems of people who have unsecured WiFi in their houses lately?

    If the whole of London (Really the whole? London is enormous, will it work in Barnet too?)gets free WiFi, that legal side of unsecured WiFi could produce some interesting legal wrangles I suspect……

  3. Karl,

    Thanks for this. I’d seen various stories about Mayor Boris’s wi-fi aspirations but nothing concrete. I suspect what I found was some sort of experimental test signal, although it’s a bit cruel to call it “Free Public Wifi” when there’s no actual connection. I intend to do more digging on this.


  4. I’ve been baffled by this all week on the Northern Line, which is (like the Piccadilly line) obviously too deep for there to be anything leaking in from above. I get one or two bars of ‘free public wifi’ but with, like you, seemingly no way to actually connect to the internet. Must be some sort of test signal.

  5. Hi Martha, glad I’m not hallucinating. There’s definitely something going on and I can only surmise it is a test for the Olympics. But why they call it “Free Public Wifi” at this stage is baffling. If I’d seen “xyz” or some other incomprehensible name I wouldn’t have been quite so suspicious. I’ve been away from London for many weeks but will try to speak to someone at Boris Johnson’s office when I return. What is so surprising is that there has been so little mention of this on the net. Now I know there is at least one other person definitely seeing this network there must be thousands who’ve noticed it. Very strange.

  6. curiouser and curiouser. The blog article you mentioned is very interesting and I now recall having seen “Free Public WiFi” in many places and in several countries (where, you would think, the name would be in the local language). As the writer says, it leads to nowhere. I can’t imagine how this happens, but we are to assume that someone in the came tube carriage is using a laptop which is broadcasting this signal. I think we can discount TfL’s “leakage down the ventilation shaft” idea since the signal appears to be constant on a particular journey. This behaviour would be consistent with it emanating from the laptop of a fellow passenger. Clearly we need to do some more digging on this and I think I might do another post. Thanks for your interest and help.

  7. Thanks for your comment. I did a later post following new information. It seems that this “Free Public Wifi” signal is broadcast by some Windows computers, so the likely culprit is a fellow passenger. That’s why we see the signal consistently for some distance yet on other days it is absent. Apparently this is common and the same come-on wifi is seen throughout the world and is purely a nuisance. So now we know!


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