PYE M4000

See this phone in action on BBC TV Nationwide https://www.facebook.com/watch/?v=2373627986259879

 Prices quoted in film are £2850 +£100 install, £17-£18 a week for line rental or lease, calls are 8p for 4 seconds at peak times

The PYE M4000 System 4 Radiophone was made by TE-KA-DE, the company mentioned as the system 4 network suppliers.

Wireless outsider mentions the radiophone here .. http://lifeatluthien.com/wireless_outsider/?p=225

The radiophone is physically very similar to the radio described here http://www.oebl.de/B-Netz/Geraete/TeKaDe/BSA31S/BSA31.html 

Control Head Cable Colour Code