Thanks for the advice, I shall follow it confident that I am now thanks to previous advice able to work out the wind regardless, the skill will no doubt become useful when in the air to work out the true uppers.
I assume I use the wind(dot) down method, when selecting the wind I normally place the card / dot and 100knots and mark on my wind speed, so if its 15 I will mark 85 knots, so this is the opposite method to what you would recommend?