Don, a Cambridge University graduate who joined Pye in 1937, was described as Pye’s best mathematician.
He played an important part in improving the reliability of the Proximity Fuze to explode as it neared its target.
Along with Dennis Fuller he helped develop the Pye Wire Guided missile, and, in 1965, the world’s first electronic pacemaker.
In 1958 he set up Pye’s Space Instrumentation Laboratory, which designed and supplied scientific experiments to go in unmanned spacecraft. Between 1964 and 1980, 30 were produced.
He retired in 1978.