EE (formerly Everything Everywhere) launched its new 4G mobile networks this morning, pledging to supporting 70% of the UK by the end of the year and 98% by 2014. But already, its networks are operational in four cities across Britain, and we’ve had the opportunity to take it through its paces.

EE says that its networks are five times faster than its current 3G networks, meaning you can download data and update your social networking feeds with a quickness. The company touts download speeds of up to 40Mbps per second and upload speeds of up to 15Mbps a second.

This is what we saw, testing devices at the Science Museum in London:

Compare this with a T-Mobile 3G (HSPA+) connection:

The four cities – London, Bristol, Cardiff and Birmingham – have been switched today and EE’s engineers will live-test and integrate the company’s systems in preparation for a wider customer launch.

If you’re in London, Bristol, Cardiff, Birmingham, Leeds, Sheffield, Manchester, Liverpool, Glasgow, Edinburgh, Newcastle, Belfast, Southampton, Hull, Nottingham or Derby, that customer launch will be before the end of the year.