The TBA, the same as BABS but you had a coffee-grinder frequency changer, was in service at Tern Hill in 1960. You found, or were directed by ATC using CADF, to the overhead cone of silence. Once there you followed the procedure and there was an outer and an inner marker.
The 'beam' was audio and on finals at Ternhill you turned right on the 'A's and left on the 'N's. The mix, a continous note was heard when on the centre line. 300 ft rings a bell and flying dual one would be told to look up just as you passed over the hedge at about 50 feet.