You can see them in action at Avoncroft Museum of Historic Buildings[0] which includes a working telephone exchange.
About a mile from there is Droitwich Transmitting Station, an ArtDeco era station, see page 13 of [1] for exposed knife switches with 400V.
[0] https://avoncroft.org.uk/avoncrofts-work/special-collections...
[1] http://www.bbceng.info/Operations/transmitter_ops/Reminiscen...