Ofcom published its first research into "..consumers' experience of mobile broadband in the UK since the 4G auction in 2013. The research measured the performance of 4G and 3G services on smartphones from the four main mobile operators - EE, O2, Three and Vodafone - in Birmingham, Edinburgh, Glasgow, London and Manchester".
Using smartphones, some 210,000 tests of 4G and 3G mobile broadband were carried out both indoors and outdoors across the five UK cities between March and June 2014 .. The research compared the performance of 4G and 3G services overall and highlighted variations between operators across four key measures: Download speed, Upload speed, Web browsing speed and Latency".
See "4G and 3G mobile broadband speeds research" - here.