Mr Holan's major interest and contribution to science has been in the mode of action of biologically active organic compounds and in the relation between chemical structure and biological activity.

Throughout his career he has sought to use the knowledge gained for the design and synthesis of useful agrochemicals and pharmaceuticals.

Mr Holan's research has culminated in the discovery of a new series of insecticides, the "Insecticidal Esters", which attracted worldwide interest from the agrochemical industry.

Orie of these compounds, with the ISO accepted name of "Cycloprothrin", will soon be marketed in South East Asia and Australia.