The following notes are from the logbook of the BLEU technologist carrying out the development: 10 March 1958 (the 38th flight of that programme): "Very little drift, about 0.3g-heights 150-55-15-0".
The following notes are from the logbook of the BLEU technologist carrying out the development Copy of Logbook for D.R. Easson, Scientist BLEU 1955-1958. Martlesham Aviation Museum document A2669/D1350: 10 March 1958 (the 38th flight of that programme): "Very little drift, about 0.3g-heights 150-55-15-0".