I have, at least once, but I'll go over it, briefly, again
Harry is an old bloke, from a small West Yorkshire (former) mining town, called Normanton. He has the broadest of Yorkshire accents. Years ago, there was a food stand in the market, which sold spicy sausage-meat balls, and Harry would always turn up with a small foil-lined bag, filled with them. He'd say, "Duz tha want 'ot ball?" We came to associate the snack with Harry, and it's how he got his name.
I've no idea what 'Nobber' actually means, as it predates my time on the market. Al, and Tool Man, and Boring Ray, had a mate called Howard, an crusty old SAS man apparently. One day, him and Al were verbally sparring, and Al called him something unrepeatable, and Howard told him, "You're worse than that, you're a nobber!" Everyone looked at each other, quizzically, and Al, apparently replied, "What the hell's a nobber?" Nobody knew, Howard said no more, the name stuck