Mola - that does make sense thank you.

So the bottom line is that;
With the idle setting that I have already : this will not stop the prop speeding up.
With the brake on : this will not stop the prop speeding up.

The only way to improve the situation is to get the Spin ESC and prog box and programme proportional braking -although based on the argument about mechanics it seems that this will not totally solve the problem ? or is it worth the expense ?