London office districts lose mobile speed at weekday lunchtimes
Crowdsourced test data shows the City of London and Westminster slowing as commuters fill the cells, while EE, Three and O2 perform differently across the capital
- London ranks last of 18 European capitals on median mobile download speed: 109.43 Mbps in Q3 2026, against 172.22 Mbps for the other capitals
- London’s 5G median fell from 200 Mbps in Q2 2021 to 133 Mbps in Q3 2026 as 5G’s share of tests rose to 80%
- Three customers record the highest median download speed across London, at 113.27 Mbps
- London’s median mobile upload speed, 11.40 Mbps, is also the slowest of the 18 capitals
- About 3,400 small cells sit on Transport for London roadside assets
For offices in central London, the choice of mobile network now shows up as a measured gap at the busiest point of the working day, in both speed and responsiveness under load, which coverage maps do not show. O2’s latency gap is not confined to peak hours or to the two office districts, so it reaches staff wherever they use the network across the capital.
“As commuters arrive, more phones share the same cells, and each gets a smaller slice of their capacity.”Luke Kehoe, research lead for Europe, Ookla
Weekday mobile download speeds in the City of London and Westminster fall to a median of 80.07 Mbps at 13:00, 27% below the same hours at weekends, according to research published on 19 October by Ookla, which sells network performance data to operators. Latency under load, a measure of how responsive a connection stays during a large download, rises 26% over the same hours.
The study, written by Luke Kehoe, who leads Ookla’s research in Europe, draws mainly on Speedtest Intelligence, built from tests that users run themselves on Ookla’s Speedtest apps, alongside background signal measurements and official statistics. The two districts hold about 1.5 million jobs but only 213,000 residents. In 2020 and 2021, with offices largely empty, the City had the fastest mobile speeds of London’s 33 boroughs. In 2026 it has the slowest.
How the operators compare
Over the past year, EE customers saw the smallest weekday lunchtime slowdown in central London, at 15%. O2’s median latency under load, at 1,573 ms, is about three times that of its rivals, and the gap stays as wide overnight, when networks are quietest. Kehoe links that to the way O2’s network queues traffic during downloads, known as bufferbloat, as well as to congestion.
Landlords can end a site lease with a notice to quit, typically when a building is redeveloped. VodafoneThree expects to take nearly 100 sites offline by the end of 2026, with replacements taking around five years. Operators have turned to small cells, low-powered radios fixed to lampposts and street furniture, to make up some of the shortfall.
Sources
- Ookla, “London’s mobile networks are running out of room”, Luke Kehoe, research article, 19 October 2026. https://www.ookla.com/articles/london-mobile-2026
- ISPreview, “Ookla – London ranks last among 18 European capitals for mobile broadband speed”, Mark Jackson, 19 October 2026. https://www.ispreview.co.uk/index.php/2026/10/ookla-london-ranks-last-among-18-european-capitals-for-mobile-broadband-speed.html
