EE has announced the launch of its new 4G LTE network in the UK ahead of a full roll-out to four major cities - London, Cardiff, Bristol, and Birmingham - in the coming weeks.

But what speeds is EE promising and what speeds can you expect to get? We managed to test the network at the launch event in London on a Samsung Galaxy S3 and the HTC One XL to find out.

The promise

Customers who move over to the new EE 4G network should be able to get speeds of up to 21Mbps according to the company. For most that will be faster than they currently have on their home broadband and means you'll be able to download a 20MB file in seconds rather than minutes. In comparison, most 3G download speeds, EE says, are around 1.5Mbs on average.

The test

Simple. Run the speedtest.net mobile app on a Samsung Galaxy S3 LTE device provided by EE and an iPhone 4S provided by us in the same room.

The possible pitfalls with the test

We were at the EE launch in the Science Museum in London and there where only a handful of devices on the network in the room. We weren't moving, there was probably very little interference and we don't know how big the antenna was in the room. We suspect that because it was the launch, the signal would be better than you could ever possibly imagine - basically perfect conditions

The results

Testing the speed while doing a video interview for the BBC with Rory Cellan-Jones, our test iPhone 4S managed downloads on the Speedtests.net mobile app of just under 6Mbps in our quick test. In comparison we managed a whopping 33Mbps on the Samsung Galaxy S III LTE - that's more than five and a half times faster.

The iPhone 4S got just under 6Mbps in download speeds on the test

The Samsung Galaxy S3 LTE manages speeds of over 33Mbps on the test

Conclusions

Repeating the test a couple of times on the Samsung Galaxy S III LTE and the HTC One XL at the launch event, the results on the EE 4G network were all roughly the same. The lowest speed we experienced in the tests was 21Mbps, while the highest we saw was 34Mbps. As we've already mentioned, we were in perfect conditions.

That said, it's clear that at the moment the EE 4G network will be considerably faster than 3G, when it launches in the coming weeks. However, how the network will perform when you are moving around (ie, on the bus) or when more and more people sign up to the service is yet to be discovered.

We plan to do a series of full "real life" tests when the network launches in the UK.

EE 4G UK: Devices, coverage, dates