The ( online ) Pye Museum

[AS.12]

Found this by accident when digging around on the topic of Queen's Flight Herons:

The history of the Pye Group of Companies in scientific & analytical instruments, radio & line communications, broadcasting, domestic radio & TV and industrial electronics from 1896 to the present day

http://ww.pyemuseum.org/divisions/communications/pye_telecom/products/v_mobiles.php

This was the paragraph that appeared in my search results:

In 1953, a PTC115 high-band equipment was fitted into the Ford Zephyr car of HRH Prince Philip and later into the De Havilland Heron aircraft of the Queen's Flight. In 1954 the equipment was re-fitted into HRH's Aston Martin Lagonda.