We took to the streets to find out just how useful is public Wi-Fi. We paired up with our friends at Broadband Genie and signed up to the three major public Wi-Fi networks: BT Wi-fi, O2 and The Cloud. Armed only with a laptop, we sent five testers on to the streets of London, setting them a series of timed web-based challenges, each to be completed at the same time in the same place. For the full story read: How good is public Wi-Fi? We test The Cloud, BT and O2 to find out if you really need 3G or 4G connectivity.

The five contenders included three testers who were allowed only to use their chosen public Wi-Fi network, BT Wi-fi, O2 or The Cloud. We also had a wildcard tester who was signed up to no accounts, but able to use any public Wi-Fi network that didn’t require direct payment. As a control we had one tester using 3G, with a dongle from Three.

This was not a scientific test. To an extent it required ingenuity and flexibility on the part of the individual tester. Consider this more of an anecdotal piece: in part we wanted to test just how much thought was required to find a usable connection. The user experience is an important part of all consumer tech, after all.

Our nine tests took us all over London, and involved tasks as varied as streaming video, finding turn-by-turn navigation and download image files. So how did we get on?

How good is BT public Wi-Fi?

In general our BT tester thought connectivity was okay, but the user experience wasn't great.

We weren’t impressed with the apps – the hotspot map wasn’t very good, for instance. And, on a laptop, it seemed as though you couldn’t go back to BT page if you’d already been there but failed to login. It would open the first time you opened the browser, but if you didn’t sign in and restarted the browser it disappeared.

Our BT tester found he had to log in too many times, and there were too many different networks to choose from. He thought it should be much simpler. But crucially he could get online almost every time.

How good it O2 public Wi-Fi?

O2 Wi-Fi was generally good. Setup online was easy, but adding a laptop as a second device proved a pain. From then on, when in range both our tester's smartphone and laptop connected to networks and the performance was great, just like being at home.

Coverage was consistently good in London, although when you’re not near a hotspot the smartphone app and mobile data is required to find one.

How good  is The Cloud public Wi-Fi?

Since The Cloud boasts of thousands of hotspots around the country. Frequently, though, it seemed that major areas were bereft of connectivity, even when other networks were available.

The Cloud generally was nearby, but this almost always involved walking to a café or restaurant. That’s fine if it’s not raining and you can stand outside, or get away with sitting in there while checking your email, but not many restaurants will let you take up a seat without paying for something.

The Cloud smartphone app proved useful for quickly locating hotspots and seemed generally accurate. One oddity of The Cloud network highlighted by the app is the clustering of the connections – you can walk for ages and not find anything, then there will be three or four in a very small area, often in adjoining coffee shops. It would be more useful if they were spread out, although it does mean that if the place you’re in is very busy you can try next door’s connection.

All devices should be registered with The Cloud ahead of time as this part of the process can be painful on a busy connection. The device-management screen can take a little while to load up and behaved strangely when the link was slow. Once that was done, though, both smartphone and laptop instantly latched on to the hotspots instantly without any further fuss. See also: The UK's best mobile networks revealed: mobile broadband group test.

And the wild cards?

Overall, our wild card tester probably had the easiest time of all. No network is everywhere but, in central London at least, you’re usually near some kind of wireless hotspot you can get on to for free.

With 3G we could get online on every occasion – as you’d expect in London. But it’s not all perfect. Streaming video was always a trial. In fact, we couldn’t get any of the videos to play properly. And downloading files on even a robust 3G connection can take a while. And that’s before you factor in cost. See also: Android vs iPhone vs Windows Phone vs BlackBerry: which is the best phone to use on the move?

The verdict: can you rely only on public Wi-Fi?

So is it true that we no longer require cellular data? Will public Wi-Fi suffice? We’d say not. There was at least one task that none of the public Wi-fi users could complete, and we never failed to get online using cellular data. But we were generally impressed by the public Wi-Fi networks. In central London they are very common, although there is an element of feast or famine. In some areas we could choose from multiple networks; in others we had to move to get online.

One regular complaint was the poor customer experience. Our test was slightly false because in most usage scenarios consumers would be set up to use their chosen network in advance. But there may be some work required on the user interface and mobile app side of things.

Nonetheless, we were pleasantly surprised at the ubiquity and quality of public Wi-Fi. In general it is super-cheap or free and, as such, it is much cheaper and quicker than is cellular data. The networks themselves all performed at a similar level – no single one stood out.
When you set out on a journey for which you will require connectivity, we recommend signing up to public Wi-Fi, but also taking along a good 3G-enabled device. (Visit Broadband Advisor for more.)