Royal Navy Leftenants?

At http://www.straightdope.com/classics/a2_136.html, Cecil relied on the word of a captain with the British naval staff in Washington, who said that the pronunciation “Leftenant” was correct in all branches of the British military. Maybe that’s so, but it wasn’t always. In 1964, Thomas Pyles of Northwestern University wrote that in the Royal Navy the pronunciation was Lootenant or L’tenant. It’s in a footnote on p. 248. I have posted a scanned copy of the page at
http://kerryspubs.googlepages.com/PylesPage.jpg