What you have there is a 1989 made Police PM rifle which someone has added an L96A1 barrel to. If you check the proof mark on the barrel you will see the year it was proofed.
The rifle would most likely have had a plain barrel with the swirly flash hider on the end. I have seen very late PM's (1991) with AW barrels fitted from new, with single port muzzle brakes, but this is an earlier one.
The later PM rifles used L96 engraved actions.
The '8' is most likely a 'rack number' added by the Police to their rifles, just to keep an easier check on which were there or missing, rather than checking serial numbers.
A nice PM rifle in L96 guise. It's an L96A1 in all but serial number.