Mobile broadband speeds in London and the surrounding area have more than doubled for existing O2 and Vodafone customers since the carriers launched their 4G services in August, but remain some way behind industry leader EE.
According to RootMetrics figures, EE's average download and upload speeds stand at 19.3Mb and 12.9Mb respectively.
Vodafone dongles came in second, recording download speeds of 9.5Mb and upload speeds of 4.7Mb.
In third place was O2, with average 4G mobile broadband download speeds of 7.1Mb and upload speeds pegged at 3.7Mb.
EE's fastest recorded 4G speed was a single test that hit 90.5Mb in Ilford, Essex, far eclipsing Vodafone’s 68.3 Mb in Ashford, Surrey, and O2's 64.3Mb just off Piccadilly Circus in Zone 1.
RootMetrics said there remains "a marked difference" between mobile broadband speeds in the centre of London and the outlying areas.
This is because 4G availability on O2 and Vodafone continues to be "very much concentrated in the city", it added.
"The results of our 86,225 independent tests across London show that O2 and Vodafone have made a great start with their 4G networks, and consumers should be enjoying notably faster speeds," said RootMetrics Chief Executive Officer and President Bill Moore.
"Certainly compared to other rollouts of 4G we have seen, London has got off to an impressive start."
Mr Moore commented that, with more 4G masts lighting up every day, speeds are continuing to increase in the capital as time goes on.
With three networks now competing for 4G customers, he urged Londoners to take "a close look at both price and performance" before selecting a broadband provider.
"Especially outside the centre, 4G is not evenly deployed, so it’s important to get a sense of which network will provide the best service where you live and play before committing," Mr Moore advised.