Anti-terror chiefs recently highlighted that the radio systems of some emergency services do not work in the deepest Tube stations.
The ability of radio waves to penetrate deeply into underground structures and substructures (by reflection) is frequency-dependent. The most recent 900-MHz and higher-frequency radios and telephones (most 800-MHz phones date from about 10-15 years ago, more recent services are above 1200 MHz) will perform in the subway tunnels, but older VHF and UHF radios tuned to the 100-MHz to 460-MHz bands will tend, like FM radio signals, to fade out inside the tunnels.
They might be able to salvage existing frequencies (avoiding the horrendous expense of wholesale changes) by introducing small repeaters throughout the tunnel network. That could work.
Anything to keep Inspector Tennyson fully supported against the horrid Wuzzies.
they need to run "leaky cable" along the lenghth of the tunnel to maintain radio operations....acts as a giant antenna.