Public Wi-fi test 5. Watch the South Bank Show at the South Bank Centre

Starting from outside the Royal Festival Hall on the South Bank, we asked our testers to find a web connection and navigate to YouTube. They then had to find and watch a clip called ‘The South Bank Show Opening'. To pass the test they had to watch the entire clip, something that proved beyond our 3G control. Public Wi-Fi fared much better.

Our O2 tester's laptop again automatically connected to a hotspot, a Yo Sushi network. They were able to load and watch the YouTube video within a minute of taking the laptop out of its bag.

Our BT tester had to enter his login details again, but also quickly loaded and watched the video.

With The Cloud we also found a strong signal even sitting outside. Once again, however, our tester had to register his laptop with The Cloud. After a couple of aborted attempts where it seemed to hang at the final step this was successful. Once that was done the video loaded right away.

Interestingly, our wildcard had better luck with the same network. Their laptop instantly logged on to The Cloud's Wi-Fi, remembering the login from Pizza Express.

SOUTH BANK CENTRE

Public Wi-fi test 6. Watch ITV at the London Eye

LONDON EYE We nipped down the river, stopping just outside the London Eye. There our intrepid testers had to find a web connection, head to the ITV website, then find and watch the opening credits of the most recent episode of 'Coronation Street'. The 3G control test got as far as the web page but was unable to stream, and the Wi-Fi networks proved similarly reticent.

Our O2 tester's smartphone app showed a hotspot at McDonalds, but they couldn't find the network. Fail. Our BT Wi-fi tester had a marginally better experience, finding a BT Openzone, and even navigating to Corrie before the Wi-Fi dipped out. Fail. There's a Cloud hotspot right next to the London Eye, but it seemed far too busy to allow our tester to finish the task. They found the page, but the video wouldn't start. Fail.

Our wildcard tester found another network in the Namco games centre, but couldn't stream the clip. So none of us got to watch 'Coronation Street'. Gutted.

Public Wi-fi test 7. Watch Wills and Kate get wed at Westminster Abbey

Having failed to indulge our taste in high culture, we headed back across the river to Westminster Abbey to find some high society. The task here was to find a connection and watch, via YouTube, the official video of last year's Royal Wedding. To complete the task our testers had only to get the video playing.

Our 3G test did manage this, although the clip was a little jumpy. Not so for the O2 public Wi-Fi. Again, our tester's laptop automatically connected to a hotspot, at Parliament Square, and the clip quickly loaded and smoothly played.

The BT Wi-fi experience was not so good. Despite BT's map suggesting that Parliament Square is one big BT hotspot, our tester could find no connectivity. The Cloud at least spared us the dashed hopes. The Cloud was not available here, although the app did show several hotspots clustered at nearby streets.

Our wildcard tester took advantage of the 02 Wi-Fi account he had set up earlier.

Public Wi-fi test 8. Post a selfie at the National Portrait Gallery

As our test drew toward a close we decided to capture the occasion for posterity, heading to Trafalgar Square and asking our testers to post self-portraits on Twitter, using public Wi-Fi to get online with their smartphones.

This was not a problem for the 3G control test, as it is the sort of thing for which you would naturally use cellular connectivity.

But the public Wi-Fi users struggled.

Our O2 user was connected, but was unable to upload the photo to Twitter or even browse the web. The experience was better with BT, but our tester had similar issues. His phone connected okay, but there were problems tweeting. He had to go into the browser and enter login details, then return to the Twitter app. Our wildcard tester used the O2 hotspot with no problems, however.

The Cloud experience was similar to that of the previous test. Our tester could find no signal in the square itself, but there was some connectivity at nearby bars and restaurants.

Public Wi-fi test 9. Find the way to your hotel from the Tube

We finished our test by using our connections to find our way from Marble Arch tube station to our hotel, using Google Maps.

The 3G control worked fine, if a little slowly. And our O2 tester's laptop had no problems automatically connecting; they were quickly able to plan the route to the hotel. That's the route down which our wildcard tester also travelled, with similar success.

The BT Wi-fi test wasn't so good: our tester signed in just outside the station, but the connection initially failed despite what appeared to be a strong signal. After a few minutes it began working and they were able to complete the task.

We had a better time with The Cloud. Here we picked up a decent signal just outside the tube station thanks to a nearby coffee shop and rapidly found directions on Google Maps.

How good is public Wi-Fi? Verdict

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.

How good is O2 public Wi-Fi?

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

"The landing page glitch was the main problem I found. 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." Chris Martin

How good is BT Wi-fi public Wi-Fi?

"I found I had to log in too many times, and there were too many different options: BT Wi-fi, BT Wi-fi with Fon, BT Openzone and BT Openzone Starbucks (the Starbucks option was generally best). As a paid-up customer of BT Wi-fi, I think it should be much simpler.

"Many of the hotspots seemed to be outside-only, which wasn't great on a wet, windy afternoon in London, but useful if you are on the hoof.

"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.

"In general, then, connectivity was okay, but the user experience wasn't great." Peter Ames

How good it The Cloud (Sky) public Wi-Fi?

"I had expected this to go a lot smoother, 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 my smartphone and laptop instantly latched on to the hotspots instantly without any further fuss." Matt Powell

How does 3G compare to public Wi-Fi?

"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." Matt Egan

And what of our wild card?

"Overall, I 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. Unless you're an 02 customer on a tube platform, at which point you're just frustrated." Neil Bennett