There has been much debate over the years since this project was initiated as to whether Wardale was mistaken in adopting piston valves driven by Walschaerts valve gear on the 5AT instead of British Caprotti valves driven by rotary cams. The issue is discussed in the FAQ pages and two or three letters on the subject appear in the Articles and Letters pages of this website.
In September 2009, Wardale received a lengthy letter raising both old and new debates on this thorny subject. Wardale’s reply in 28 separate points is reproduced on this website at his suggestion.  It may be viewed in both html (website) format and in PDF (printable) format.
Wardale’s defense of the use of piston valves on the 5AT is quite lengthy but it makes stirring reading.  It remains to be seen whether it ends the debate, but his closing comments suggest that he will not take it up again unless presented with detailed calculations that disprove his conclusions.
Wardale’s responses cover 7 pages of this website, the first of which can be found here.