Just to let you know what happened...
An engineer working in the telephone exchange at Baker Street, powered down the UPS as well as the main power to it. The engineer thought that the equipment was for connect and shouldn't yet be live.
Instantly the Line Control offices lost power to all phones, far worse than losing the train radio. This effects the whole of the Bakerloo, the north side of the Circle, entire Metropolitan line, Hammersmith & City between Hammersmith and Liverpool St, the Picc between Rayners Ln and Uxbridge. The Jubilee was largely unaffected, however Neasden control was unable to contact the SCC which controls the old part of the line.
The desision was made (on my line at least) to detrain and run trains empty in the hope that as soon as telephones were restored services could be resumed quickly.
Hope this helps.