My guess would be that he left England many years ago, but returned to die there, for whatever reason. Because of the time passed nobody who once knew him recognized him.
This is how I'm thinking too.
But I'm mystified by why he chose the moors, especially as we know the last stage of his journey began in London. He didn't choose the moors because he wanted to die in a beautiful rural spot. We have plenty of those in this country, places that aren't creepy. The moors, especially in the winter feel desolate, lonely, foreboding. Maybe that's why he chose them?. :thinking: I can't help but think he had some connection to the area at one time.
And why did he choose strychnine.