They also owned Aerad ? International Aeradio, Ltd. for charts etc.
International Aeradio did a lot more than charts - they ran training courses for foreign airports, fitted telephone exchanges in various places (I worked for a guy who, while with Aeradio, installed the first telephone exchange in Abu Dhabi in a mud hut!), maintained radio in aircraft and ATC etc, including providing a servicing facility for shipping ins some places in the Middle East He also did a radio training course for the Syrian Air Force, which subsequently got him in gaol in Damascus! Sometime after the course, there was a coup in Syria, and his BOAC flight to London was ordered to land when they were following the flight plan and were in Syrian air space. Everybody who had Syrian stamps in the passport were hauled off to prison: Don was lucky because the new government included people who had been on his course, so he was released pretty quickly. One of the guys in the prison was one Emil Savundra, later infamous the Fire Auto Marine insurance scandal.... for which he was a guest of Her Majesty for some time...