Since more than 80 viewers have nothing to add I will make a comment or two to myself if this is not against forum rules.
Charles Hayward suggests an optimum peripheral speed of 9,500 fpm.
My old Coronet Major delivers a top speed of just over 10,000 fpm at which speed the blade in question is sweetness itself. However, dropping down to the next pulley, and getting just over 9,000 fpm, the whining is quite unacceptable.
I don't suppose for one moment that Mr Hayward based his optimum blade speed on this kind of observation but it remains interesting that his recommendation answers my current problem.
Of course these comments don't answer the question as to why the screaming occurs but nevertheless the practical issue is solved.
Thank you Fred for these thoughts.