My Dad was a founder member. The 50 Club was set up by 50 original members who were mostly Leith business men. It operated out of the club rooms you are talking about and was independent from the football club. A few years before the old main stand was replaced, Hibs invited them to move into the old Toyota Lounge in the main stand with seats behind the directors box. The members agreed and sold the premises on Albion Road. When the new stand was built, they were not offered an alternative venue in it and that pretty much signaled the end of the club. Many of the members still attend but sadly some have now passed on. In its heyday the players would often head to the 50 Club after games for a few refreshments and mingle with the fans.
Iím sure some can offer more details (and probably correct my recollections).