Ok..
Tutting, laughing, eye rolling, frowning head shaking etc etc..
All the above are fully permitted and no offence will be taken!! 
Had a thought on a way to find out if it was 1 side or both or at least to maybe prove that I'm not measuring kift..
I took my cleanest thin straight edge I could quickly lay my hands on, balanced it on the surface plate with a light behind and then gently stoned it until it would sit on its edge with no light showing under the edge.
Laid it against the dovetail with a pair of end mills behind for repeatability and a consistent angle as close to 90 deg to the dovetail as possible.
Repeated each side in several positions to confirm repeatability… it seemed to show something I can work with!
On the non gib side, no mater where I set it I could not get a 1 thou feeler gauge between edge and dovetail, this is the side I did a wee bit of scraping on.
On the Gib Side, in the mid section in the same area I was showing the biggest reduction in when measuring with end mills and calliper, also where the biggest protrusion of the gib was when trying it in the saddle I could easily get a 0.07 / 2.8 thou feeler gauge in the gap and this reduced towards either end of the column.
At least I have something to work with… I think!
The above laughing, tutting, head shaking etc may now commence…

