I had just come home from a protracted springtime tour of English gardens. Perhaps it was their ravishing fresh beauty, or their complexity, or their immaculate neatness, or perhaps I had just seen one topiary box spiral too many. Most likely, it was the stark impossibility of ever achieving in my garden anything approaching the quality I had seen elsewhere. Whatever the reason, a light melancholy descended on me, like a thin summer rain. I went deliberately to the bookshelf and took down a book which I had not read since it was first published in 1997. I needed a dose of Geoffrey Dutton – poet, gardener, professor of medical science, white-water swimmer and mountaineer – to help me regain my usual cheery equilibrium.