It is indeed the 39-45 Star. These were made by various contractors and therefore have various minute differences. This one appears to have been subject to sunlight as the ribbon has faded badly. It is a British awarded medal, those to South African and Australian forces had the service persons details stamped on them. This has been a bone of contention for British veterans who saw it as a slight that the labour government couldn't even be bothered to stamp up the medals with their details although those of WW1, 6.5 million war medals alone, were done. I don't know what has caused the shiney patch on the rear but you need to clean it off, the copper of the medal can leach out and it will be permanently discoloured.