Context was a conversation I overheard. Someone was asked a question (can't remember what) and they replied with "I'm a bit to the left on that one" it was definitely them disagreeing with what they were asked but I was just wondering what the origin of the phrase is when using the word "left".
Given the lack of context, my guessis that the person might have meant that they have a somewhat liberal view or stand on the issue (whatever "that one" refers to).