The Hal an Tow as performed at Helston isn't a dance but is a type of Mummer's play. The players are people of all ages who run through the streets blowing whistles and Shouting OGGIE OGGIE OGGIE OY OY OY!. The play begins with an address of welcome in Cornish and then the song begins. after each verse a short play is enacted the first with St. George killing the dragon and the second with St.Michael Killing the devil.
I haven't checked out the tune given by Bruce yet but the tune used at Helston isn't the one used by the Oyster Band etc.