I went to the Shilo museum yesterday and got the answer to my question. I was there to get some photos of the C1 howitzer they have and asked what they had for limbers. Clive took me to the far end of the building where this resided under a tarp.
It is identical to the one I got. I even recognise the various cast brackets and footman loops I found in the ground. Obviously I have to do a bit more digging yet to get everything.
The wheels are much more complex than the farm wagon wheels that are so commonplace around here. This limber is a bit out of my normal collecting range, so I am not sure what to do with it. I may do a quick restore in the spring and put it out front for a lawn ornament.