The first marking are import marks denoting the calibre, country of origin and the importer. They were applied so it could be brought into the US
The second set say it's a No4 Mk2 made at Fazakerley in Jan, 1952. These are the manufacture details of the rifle.
Looking at the pics it's been chopped down to look like a No5- something that was not done at the factory. Very tidy, but not an original "jungle carbine"