The change in the design of the baseplate was done on all Tech razors regardless of origin sometime in 62 or no later than 63. Go look at tech razors made in 61 and 64 on ebay to see the change. Your English one is 62ish or later and the American one 62ish or earlier. With that said the Pyscho Tech razors were meant to be safe not and are not good performing shavers for that reason. Nice collector pieces for a shave cave but not a daily driver type of razor.