Geograph - photograph every grid square

Back in the years BS (before silicon) long distance telephone circuits or trunk lines needed valve amplifiers to maintain the signal strength. In rural areas repeater buildings such as this were built at intervals of about 18km. As well as the amplifiers themselves it housed a battery room and a standby generator. At about 6km in either direction were subsidiary repeaters such as NY5506 : Former Telecom Substation at Shap Summit. They housed amplifiers only, power being fed to them over the telephone cables from main repeaters such as this.

See Fenny Stratford repeater station Link and, an unlikely source, Riverside Church Link (Archive Link ) a trunk repeater turned into a church (with bomb-proof rooms to protect them from the wrath of God).

Nowadays a fibre optic cable can go as much as 100km without needing regeneration so repeater equipment can be located in telephone exchanges. Or on the rare occasions where separate repeaters are needed, they are small enough to fit down a manhole.