Professor Threadgold's book follows in the steps of Ward, Hewitt, Harding, Marinaro, Swisher and Richards, and more recently, Goddard and Clarke. All of these authors have taken a critical look at how flies appear to trout, and several have attempted to redesign the dry fly, with widely varying results. Now it has to be said that traditional hackled dry flies do have some glaring faults, but the fact that they most of the fish some of the time satisfies the majority of anglers, and innovative dry flies seem condemned to die a lingering death; witness the eclipse of Goddard and Clarke's USD series. That aside the professor's book is an excellent effort, if rather densely written. There are two excellent chapters on trout vision which, while not easy stuff to get through, ought to be compulsory reading for every fly fisherman. The remainder of the book concentrates on the professor's 'footprint' flies, which are a cross between Marinaro's 'thorax' flies and parachute patterns. While the footprint flies are very different, they are designed to be easy to tie and I am sure they will catch a lot of fish, even if they don't revolutionise fly tying.