 After graduating from agricultural college he became a nurseryman and self-employed landscape gardener, then opened his own garden centre ("The Hamilton Garden Centre") on the outskirts of Kettering in Northamptonshire.He began writing a column for "Garden News" in 1970, and in 1975 became a full-time journalist when he took over as editor of "Practical Gardening" magazine, where he began his crusade to inform everybody about the joys and benefits of organic gardening.Hamilton got his first break into television in 1970 presenting "Gardening Diary" for Anglia TV which led to guest appearances on BBC1's "Gardeners' World".