HC Deb 31 March 1909 vol 3 c319
Viscount VALENTIA (on behalf of Mr. Renwick)

asked the Postmaster-General whether he could state if underground telephone lines were as efficient as those above ground for long-distance conversations?

The POSTMASTER-GENERAL (Mr. Sydney Buxton)

The answer is emphatically in the negative. The transmission of speech over underground telephone lines is much less efficient than when overhead lines are used, and speech over underground cable becomes practically inaudible at a very moderate distance.