  We discuss exclusive $J/\psi$ photoproduction, initially in conventional
collinear factorisation at NLO and then subsequently in a refined approach with
a programme of low $x$ resummation and implementation of a crucial low $Q_0$
subtraction included. We compare and contrast predictions in both frameworks
and remark about the possibility to constrain and ultimately determine the low
$x$ and low scale gluon PDF, emphasising the significance of this for future
global PDF analyses.
