He wasn't off by 200 miles. That's just how far the source of the stones is away (both the location he gave and the new one). You should probably read the comment again.
Oh, I got that wrong while reading the article too then.
Yeah,the article is worded very poorly (misleadingly?). I just measured the distance between the location Thomas originally gave (Carn Menyn) and one of the two new locations (Craig Rhos-y-felin) and it's about 4.5 kilometers.