Since its publication in paperback in 1974 I have used this as my standard reference book when my family and I have been out on walks here in the Lake District. I find it invaluable and once you start to use the keys and methods to name that unknown flower, which you have just probably stood on!, then it becomes obvious that this book is essential to furthering your study and enjoyment.The comprehensive aspect is an essential feature and this work done by Richard and Alastair Fitter in the 70s still remains a classic book; the illustrations by Marjorie Blamey are a delight to see and use. I got a second hand copy here on Amazon the other day for a few pounds and now I have one for home and one for out in the woods,fells and fields. Try it and see.