Ralph Whitlock, in The Grey-Green Plain, the first chapter of his book Wiltshire, published by Paul Elek, in 1967, wrote:
It is a curious fact, by the way, that, whereas in tropical lands orchids are generally flowers of luxuriant forest country, in England the greatest variety of orchids is to be found on the high, dry downs. Within a few miles of my home on the edge of Salisbury Plain I have found the following thirteen species: Green-winged Orchis, Early Purple Orchis, Dwarf Orchis, Spotted Orchis, Pyramididal Orchis, Fragrant Orchis, Frog Orchis, Butterfly Orchis, Bee Orchis, Twayblade, Bird’s-nest Orchis, Broad-leaved Hellebore, White Helleborine. If I were an expert botanist I feel I could find more.