What are the slide positions for a "G" bass trombone?

This is an obsolete instrument of English origin once used in orchestras, military and brass bands. After being abandoned by professional players in favour of the wide bore Bflat/F it continued to be used for some years by amateur musicians especially in the brass bands. I put a request on a proper trombone site without success so I am hoping that there is someone out there on Fluther who might have the answer.