Hi everyone, or should I say howdy as this is directed more at our American friends. I'm in the UK as you can see and yesterday I had another of my impulse buys

I bought a signal canon. Its a W.R.A.Co (Winchester) 10 gauge/bore blank firing gun as used to start boat races etc.
I need some help in identifying it so I'll tell you what I know so far..... the carriage is cast iron and looks to be painted with black enamel, the barrel is chromed steel, under the barrel its stamped 276, on top its hard to make out, it looks like a bad stamping of "manufactured", along with 2 symbols I dont recognise. From the condition I would guess it has some age. I tired to show the condition in the pics, it has a few tiny dings and some slight pitting, but its sound and is operational, I would be grateful for any help in dating etc, which brings me to me next question, more for my UK friends......
First off, I dont fancy being arrested

ok, prison food is pretty good now and it would get me out of the bedroom tax, but I have a bad back and bending in the shower would be a problem ( I cant straighten up quickly these days). From what I've read 10 gauge is classed as obsolete caliber so it should be ok, its also classed as "collectable", does anyone know for sure ?
(10gauge cartridges which are classed as antique/obsolete caliber under section 58 (2) of the firearms act)
Not sure where this should go ! more help needed !