You may be interested to know that on a visit to our local meadow two days ago I was surprised to find a pure white orchid which is probably a white version of the Pyramidal Orchid. It is said to be a rare occurrence. There is a photograph in the book which can be seen from the web site linked here
Britain 's Orchids
A guide to the identification and ecology of the wild orchids of Britain and Ireland
David Lang
(interactive version)
This website is a fully interactive, searchable version of the book; Britain's Orchids, published jointly by English Nature and WILDGuides
Web site link: