However, what you hadn't fully appreciated was just how independent-minded this characterful terrier can be. You can be out in the park and it's as if someone threw a switch. The normally well-behaved dog gets sight of a squirrel and becomes oblivious to you. So far there's been a number of near misses where the dog took off across a field and ended up on a road.
It seems the very thing that appealed to you about a Border terrier, their independent spirit, is also the thing most likely to bring a premature end to your relationship.
However, this doesn't mean that Border terriers are untrainable. They can be taught a solid recall, but it requires the right motivation and making training into something fun and interesting for the dog. Then with plenty of practice, your Border terrier will become a veritable boomerang of a dog.