Photo: Policing the depths of the Tube

Almost 40 foot below sea level in Westminster Tube station, a police officer fires up a radio.

The call is made possible by the Airwave emergency communication system which now works throughout London Underground.

With Airwave working underground for the first time, no part of the metro system's 250 miles of tunnels will be outside police communications coverage.

The system links 125 sub surface stations, bridging the coverage gap that left emergency services struggling to communicate in the tunnels around Russell Square in the wake of the July 2005 bombings.

The £107m system was fully operational by December 2008, five months ahead of schedule, and has funding to run until 2018.

Speaking at a demonstration of Airwave today, deputy chief constable of British Transport Police (BTP) Andy Trotter said: "From an operational point of view this will give us exactly the same abilities underground that we have overground.

"I was on duty throughout the 7/7 bombings and being able to communicate while managing the recovery operation in Russell Square would have made a very big difference."

Photo credit: National Policing Improvement Agency