Six yards is official. There is a great book, called, I think, "Ring my Bell" you can read to get a really nice picture of the game as it was.
Here is some info:
"Ring my Bell: an Old Black Country Sport" by Frank Spittle, from whom copies are available at "Ridegway", Victoria Road, Fallings Park, Wolverhampton, WV10 0NG; £3.95 plus £1 post and packing for UK.