Well it looks like I have found the issue...
somewhere along the line someone has pikey bodged the front axle and spacers...
What should have had the sleeve spacer which has the 1mm wall which slides in to the 17mm ID bearing was clearly lost and someone had inserted a 40mm x 15mm bearing and used a spacer from an older DT in place of the correct one.. The joys of owning an unknown modified bike!
So I am now getting a spacer machined up and I should be good to go! 
It has only been holding me up since before christmas.. so now I can get the wheels fitted, get the bike back to mine and do the final few bits before MOT.. starting to get excited now
Picture of the spacer that I should have had below:
Versus the spacer that someone had installed and was somehow using..
