Either no one else has this problem or I'm in Coventry.
I contacted GSHu through my reseller, Applecore:
http://www.applecoredesigns.co.uk/
They suggested re-sizing the object -in the object dialogue- to fit the 2D image.
However I over-layed the survey which indicated that it was the 2D image that was too big so I amended the 2D script to match the object size from -
ADD2 -495.998, -371.998
DRAWINDEX 1
FILL 1
POLY2 4, 7, 0, 0, 991.996, 0, 991.996, 743.997, 0, 743.997 DRAWINDEX 50 PICTURE2 "GE Snapshot 3.jpg", 991.996, 743.997, 0
IF HotspotsIn2D_Insertion THEN
HOTSPOT2 495.998, 371.998
ENDIF
IF HotspotsIn2D_Corners THEN
HOTSPOT2 0, 0
HOTSPOT2 991.996, 0
HOTSPOT2 0, 743.997
HOTSPOT2 991.996, 743.997
ENDIF
to
ADD2 -447.432, -336.683
DRAWINDEX 1
FILL 1
POLY2 4, 7, 0, 0, 894.864, 0, 894.864, 673.365, 0, 673.365 DRAWINDEX 50 PICTURE2 "GE Snapshot 3.jpg", 894.864, 673.365, 0
IF HotspotsIn2D_Insertion THEN
HOTSPOT2 447.432, 336.683
ENDIF
IF HotspotsIn2D_Corners THEN
HOTSPOT2 0, 0
HOTSPOT2 894.864, 0
HOTSPOT2 0, 673.365
HOTSPOT2 894.864, 673.365
ENDIF
And the object now behaves correctly. However I still don't know why or how this has happened so it's worth checking that 2D and 3D match.