Pye pioneered the use of UHF frequencies for short-range communications and the PF1 was widely adopted by the Home Office for local communications by all police forces.
The PF1 featured separate transmitter and receiver units. The receiver was carried in the top pocket where its upward-facing loudspeaker could be easily heard, and the transmitter was carried separately and only used when making a call back to police control.
This equipment was made in small quantities for UK Prime Minister Harold Wilson.
Harold Wilson objected to obvious or overt security precautions around him.
This PF1 based UHF radiotelephone was styled in a manner similar to a domestic transistor radio, in order to provide a short-range communications facility, but not to be too conspicuous for the Prime Minister.