Interesting article on The Royal Artillery, The Leisure Hour Magazine, Volume 4 1904-04, London, Page: 323-30. There are a couple of good equestrian shots.
https://books.google.com/books?pg=PA323 ... ry&f=false
Interesting quote: “It was at the battle of Warburg, in 1760, that Captain Phillips astonished the whole army by bringing up the guns at a gallop; and in 1793, as was stated above, the Royal Horse Artillery was first formed for the very purpose of galloping. And so the growth goes on both in tactics and in guns.”