An interesting token.
There's one site to search on that I use regularly...http://www.coinsandstamps.com/forei...ns/index.htm
A lot to go through though.
Also it was fairly rare to have 6d tokens before the mid 1800's, most were 2d, 1d or less so the odds would be on it being later. I understand that they were used as small change in those days, and 6d would probably not have been thought of as 'small change'.
Good luck with the search; I spent 30 minutes on it and got nowhere really.
A lot were made in Birmingham so it may be an idea to start the search there for local ones.
P.S. Have you considered that it may be a gas meter token from around the late 1800s. Prepayment meters were constantly being raided by burglars and gas companies changed to using tokens to thwart them. There was also a Bolton Gas Company who issued tokens, although the one I found was for 1/2d I believe. Just another avenue to try.