Probably a 1200 C. Those should be Parker Hale bases and Parker Hale rings - no other brand of ring will fit those bases, and no other brand of base will fit those rings, that I know of. The front base is correct - a #22. The rear one should be #28. Evidence on both those bases that the "divot" is extruded on forward edge - they should be round, not oval. The front ring is a correct RALS Parker Hale ring with a stud. I do not know what your rear ring is - it is not a Parker Hale ring that I have seen. Obviously not a correct partner to the front ring. Each ring should have a stud on the underside that engages into the divots on the bases. Means those rings were loose, allowing the scope and rings to move on the bases under recoil. The studs are also likely deformed, can't tell from the picture if the rear ring even has a recoil stud. The studs can be reversed to use the "fresh side" and both bases can be replaced, although most box stores won't carry them - last made in the 1960's or thereabouts.
There are three screws holding that action in the stock - up through the trigger guard assembly. You will see the big ones behind trigger and ahead of the "clip" - there is a third smaller one. You have to tap out the hinge pin for the magazine release, and remove that release - up inside, hidden by the release, will be a third one - small Allan head screw - and that is a british thread screw - either 4BA or 5BA thread, I don't remember which - damn near impossible to find in Canada - I have ordered replacements, but from Great Britain.