Its been great fun researching it and thats what I like about these things.Sometimes I buy and old picture and research the artist and the location then either keep it or sell it , anything interesting or unusual that catches my eye.
With the cannon I have found the proof marks (all the plate was painted over) and managed to enlarge a photo of it on my computer to read it. It is a Birmingham proof mark dated 1969 as well as I can tell (cross swords , letters U for date, B for Birmingham and number 1 for testers ID . The black powder proof mark is pre 1974, so I guess we're looking at something made around 1969 probably.
So its about 43 yrs old ! Im amazed how easily it cleaned up.
I have been informed that because it has a proof mark and could be in working order it would require a Section 1 Firearms certificate.If bore is less than 2" (as this one is) and its kept as an ornament then it is exempt (according to this article I read).
I am now geting in touch with the Birmingham Proof House museum to track down their records to see if the manufacturer was listed and any other info.
I shall post the results when I get them.