[1] Grundy received his secondary education from Malvern College, to which he had obtained a Major Scholarship in 1931, and from which he graduated in 1935.
Shortly after the end of World War II, Grundy moved away from the field of algebra to take up work in statistics.
During his time at Rothamsted he performed most of his published statistical research, which included investigations of problems in the design and analysis of experiments, sampling, composition of animal populations, and fitting truncated distributions.
During this period, he collaborated with Michael Healy and D.H. Rees to extend Frank Yates's work on cost–benefit analysis of experimentation.
The results of this collaboration were reported in an influential paper, Economic choice of the amount of experimentation, published in series B of the Journal of the Royal Statistical Society in 1956.