Good news for mobile users on the London Underground

Around one in five mobile connections below ground on the London Underground now run on 5G, according to new data from Ookla.

The Greater London Authority (GLA) and Ookla published the figures in their report A New Lens on the Connected Capital, using Ookla’s signal scans from about 96 below-ground station zones. Ookla collected the data between 25 March and 30 April 2026.

The report shows that signal strength in covered tunnels held within 2 to 3 dB of the street directly above, even at depths below 20 metres. The report credited that result to the antenna system Boldyn Networks installed inside the tunnels themselves.

Boldyn holds a £1 billion, 20-year concession with Transport for London (TfL) to deliver 4G and 5G across the network. It began installing equipment in tunnels serving the Elizabeth line, Northern line, Metropolitan line and others from June 2021.

By early 2026, 62 of 121 subterranean stations had high-speed mobile coverage. High-speed mobile coverage also began rolling out across the Elizabeth line’s tunnelled sections from July 2024.

The concession also covers London’s streets. Boldyn has access to over 80,000 fibre-connected TfL street assets across Zones 1 and 2, including lamp posts, CCTV poles, traffic signals and bus stops. The deal also gives Boldyn 2,000 km of TfL ducting and 400 km of underground fibre.

By October 2025, Boldyn had installed more than 200 5G-capable small cells on TfL street assets in central London. EE, Vodafone, Three and Virgin Media O2 can all connect to the network.

Live locations include King’s Cross, Waterloo, London Bridge, Old Street, Hyde Park Corner and the Shard.

Boldyn’s deployment model takes about three months from order to activation, because the ducting, power and fibre already exist. Boldyn cited download speeds of up to 300 Mbps in high-demand locations.

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