That's interesting work to do too, several of my colleagues defected to Decca Survey to work with Hifix and Pulse 8 at the time.
I did some time aboard the H class RN vessels running the Master Stations of our LAMBDA (Low Ambiguity Decca) system so you were always working on the base line with minimal errors in daylight hours. We calibrated the system using Tellurometers back them (before GPS). I remember well calibrating in allowances for wave front tilt as a function of the changing tides
The function was to enable the RN to sound and plot their charts for the Hydrographic Office charts who are in your neck of the woods.
All good clean fun and visited some very interesting places, this would have been just prior to Hyfix as it and Pulse 8 superceded Lambda.
They utilised some of our old masts to set up their Differential landbased Tx.
Happy days.
