I have began a small historical project related to some the guided missile development work in the 1950s in what was de Havilland Propellors in Hatfield, Hertfordshire, UK. I wish to get in touch scientists and engineers who were employed in the R and D sections and while I have some names, I would like to contact others. I wonder whether any subscribers to Mersenne have any advice to offer with regard to locating now elderly researchers and developers. Thanks Colin Hempstead