This is a model of a Naval Cannon or Signal Cannon.  It does not appear to be a working "signal cannon", as the touch hole is not bored through to the firing chamber. Miniature cannons like this were made for actual use, as signal canons,  or by cannon foundries as examples of what could be supplied – effectively as trade samples.  There are no foundry markings on this specimen, but it has a large embossed cartouche of a “GR” Royal Cypher beneath the symbol of the British Royal Crown. The GR indicates King George Reign. This is a machine turned cannon and as machine turning of steel was introduced into manufacture during the Industrial Revolution, it was most likely made post 1760 and it could date to as recently as late 20th century. The later the production date the less likely it is a trade sample. 

I purchased the cannon from an antique dealer – 20 years ago – who maintained it was a trade sample, produced by an actual cannon foundry.

Its design closely follows the drawing from the Royal Armoury archives of a 17th Century cannon. (Please see final photograph). The trunnions are located below the centre of the tube and this dates the design to before 1725.  (The introduction of the Cronstedt system coincided with the trunnions being located at the mid level of the inner chamber. Before this, they had been placed below the centre line). The design has the characteristics of the most noteworthy examples of Royal Navy cannons of the 18th and early early 19th Centuries, which include the following characteristics: prominent cascabel knob, reinforced chamber, lower than centre-line trunnions, and five reinforcing bands.  Whatever its intended use, it is an extremely rare piece and I have never seen or encountered a cannon in both bronze and steel like this one. (I have done lots of research on it) It is in excellent condition and is a pleasure to hold. It measures 25.5 CMS. It weighs 600 grams.