John, the photo of C. ÂBlue Steel as stated in the RHS trials was submitted by B. Williams. I think this photo was submitted by Brian prior to the trials. All the trial entries were grown in containers and as you see, this canna photo is not in a container. (At least the one I found) You might check out his web site by doing a search for Brians Botanicals.
I made a quick check of his site and at the present I did not see any cannas listed. I do not recall how this cultivar did during the trials but there were a number of cultivars that were never included in the viewing (judging) areas for one reason or the other.
The best information about any of these results needs to come from the UK trial administrators. No doubt that the colors of the canna leaves are genetic related and are usually in the range of green to red (burgundy). The idea of a true blue is likely not possible and may be the result of photography? No deceit implied. We often see leaves that are described or appear as blue-green etc. There are a number of red leaf shades of canna leaves in the marketplace. Old historic information tends to promote the specie canna warscewiczii as the origin of our red leaf cannas?
Regards,
Kent

Kent,

Thank you very much for the information. I will get the plant C. warscewiczii (or maybe seeds from it). I am not really a collector. The few cannas that I have are mostly from seed. I am aware that seedlings will probably be inferior to their parents. However, I enjoy doing it, and figure there is no better way of getting plants that will do well under my conditions.

Thanks,
John