Working like Billy-o! What does it mean?

Having a conversation yesterday about one thing and another, and someone said to me "Yeah I've been working on it like Billy-o; whatever that means"This set me thinking yeah what does it mean? I know I've used this saying myself quite often.For me it mean's Fast - Hard - All the time!Am I right in thinking this? Is other peoples understanding of this saying the same? Does Billy-o mean anything?