Virgin Media has started to roll out its new Wi-Fi service in stations in the London Underground from 7 June with the promise of up to 120 stations by the end of the summer. But is it easy to use, does it work, and are there any restrictions?On launch day there are just two stations where you can use the new free service, however Virgin Media says this will quickly grow to more than 80 by the end of July.From 7 June passengers can get online and stay in touch with the world above at King\u2019s Cross and Warren Street Tube stations. Oxford Circus and Green Park Tube stations will go live from 8 June, with Victoria and Euston going live on 9 June, meaning passengers on the Victoria line will be the first to benefit from Wi-Fi, says the company.We picked the Circle line platform at King\u2019s Cross.Get into the Tube station and a quick search on your phone for Wi-Fi networks will reveal the Virgin Wi-Fi wireless network allowing you to connect and start surfing with little hassle.Once connected, all you have to do is fire up your browser on your phone, tablet, or laptop, say yes to whether you want to access the service, and then enter your email address and tick to agree the terms and conditions.Once done you are redirected to a \u201cwelcome page\u201d before being able to use the internet as you would at home.In the case of our testing we used the new Underground Wi-Fi service on a Nokia Lumia 800 and our MacBook Air.The first port of call was to check out the latest news, reviews and features from the tech world on Pocket-lint. All good, no problems.\u00a0The next test was to give Skype a go. We had no problems on either device (yes we know the Lumia 800 doesn't have a front facing camera but that made it all the easier to show the trains off). Virgin Media isn't blocking the app on the two devices we tested and that means that you can now have a call with your friends from the bowels of London. This being the first day, we did get a couple of looks.The third test, Pirate Bay. Virgin Media broadband customers have been blocked from the service and so have its Underground customers too.Beyond that we tested surfing the web, emailing, and generally all you would do on the web for around 30 minutes. All worked fine, although we did find that after about 10 minutes the service dropped connection. Turning off Wi-Fi and then back on again fixed this and we couldn\u2019t work out whether there was an automatic time-out feature or not, although we suspect there is. We weren't asked to sign in each time.\u00a0Performance wise we didn\u2019t do any speed tests - really who cares - but the connection is fast enough for you to load up with new emails, watch YouTube, tweet, surf some pages, and update your RSS reader on your phone so you've got something to read on the train immediately after.Trying to keep the connection as long as possible, we lost it at about 30 seconds into the tunnel as we left the station. Remember, the service is for platforms only at the moment.\u00a0If you find yourself on the platform needing to check whether you\u2019ve received that email, this is going to be a godsend. The system at the moment is very easy to use and signing up involves minimal fuss. Whether that will be different when Virgin Media begins to charge for the service is yet to be seen, however for now, if you like being connected you are going to love it.