BOAC
My point, not very clearly expressed, was really that 'forward speed' is an expression of Dozy's; I am sure that AB's engineers knew and know very well that it is the total air speed over the vanes that drives them not forward speed alone. [and so does Dozy I suspect, it was probably just loose wording]
In normal flight the two speeds are identical to all intents and purposes, although not of course when descending at around 10000 fpm (100 kts) and a forward speed which is also around 100 kts. Which is where the confusion between HN39 and rrr starts
Not worth flogging!