The enclosed drawing is from the book on British Quick Firing artillery by Len Trawin. It has some excellent illustrations and cut away for the 4.5.
Also included is a section on the types of wheels.
The 18pdr and 4.5 used the same wheels, as did the limbers.
The official designation was 2nd class 'C' No 45.
You can see the spokes are offset to the next one around.
Yes, both the 18 pdr and 4.5 were quite important, the 4.5 fired over 25 million shells....the 18 pdr 99.3 million.
George.