One additional point that may help someone trying to decipher what i’m complaining about…
If you press shift + v, which brings up the ‘view menu’ then you select the 3D camera & go to its co-ordinates on the right hand side, zero’ing the ‘B’ axis levels out the viewport, correcting the ’tilt’ i mentioned above.
Now, this used to be a constant – my viewport seemed to never have this ’tilt’ which now occurs whenever you rotate the perspective view.
Hope that helps explain my predicament a little further.
Thanks