Hi Ian
great model of my favorite ship
I have been building her at 1/144th scale on and off for the last couple of years,and I know the scarcity of information
There are some good photos of the 4.5 mount and the vickers guns at the following site
the dock museum
"the vickers photographic archive"
go to armament>naval weapon>naval gun
photos 28 to 33
keep up the good work
John