Results at last, so simple I don't know why I didn't think about it in the first place. My frustration was leading me to almost strangle the grip!
A light grip has added 30 plus yards, also added distance through my
irons with the same change, 20 yrds to my seven iron (about 140 yrds). This was with poor quality range balls, so hopefully on the course this will go up a bit.
Still work to go to get up with these 300+ yard drives you are all hitting but for now I am happy with my drives going 230-250 yards where I aim them.
It just shows, always look at the basics first, after going through all my setup and posture I looked for a complicated reason for the fault rather than the simple ones.
Thanks again for all the input, there are definitely good points that will help me gain further distance once I have embedded this change.