It is not the type of screw(i see both a phillips and a standard screw) , but that it has screws at all, rivets probably held the badges on originally so the badge on this bike may not be original to it and can not be used to reliably date the bike. Parts are easily swapped out over the years, but the stamped-in serial number on the frame is a solid bit of evidence if it can be seen.
With the prices of some old bicycles up so high I would not be surprised if some profiteers fake serial numbers too as has been done in automobile and motorcycle collecting( I have seen first-hand a guy weld-up the numbers on a frame of a few British motorcycles and re-stamp them). This bike has a pretty good looking patina, so I am guessing it has not been through any sort of restoration-mill or a lot of parts-swapping.