look on top of the rear of the barrel. Does it have Parker-Hale written there? If it does you dont just have a regular converted sporter. The Parker-Hale rifles are saught after by a special breed of collector. If it is a Parker the foreend is different than mine but the rest appears the same. Get a 10 round magazine for it, thats what the Parker-hale guns came with. The reason I'm thinking it is one is the P in the corner of the top of the rear sight I see in one of your pictures. Parker-hale built sights to replace the two position flip sights used on many of the WWII Brit built rifles that were machined units like the original but too material and time consuming to use in mass quantity mk1 sight the No4 mkI was originally meant to come with.
I shoot mine only as a hunting rifle now, it'll peg a milk jug repeatedly at 200 yards with the peep sight. really nice rifle.