Cash Against Leaves: A Viable Option
"Cash against leaves" is a viable option if there's no cash-flow problem in your company.
If you want to avoid any cash outflow or just don't want to go for the "Cash against leaves" option for whatever reason, another option could be to reintroduce the "carry forward" option, with limitations (a maximum limit of leaves that can be carried forward).
However, you haven't answered my query regarding the "reasons" for the decision made by the Directors 4 years ago—they must still be around. It's quite possible that a temporary cash-flow problem at that point in time could be the reason, which can now be normalized.
One more option to avoid any backlash from the employees, for no fault of theirs, could be to have a one-time "Cash against leaves" option considered and then make the future policy clear to them now.
Management Considerations
Another important point for the Management—usually, all high-level meetings end with minutes of the meeting being made and circulated. Obviously, this seems to have not been done, or there's no such practice in your company (had it been there, someone who attended the meeting would have definitely noticed it then). Just check and correct the situation before another similar situation arises for any other issue.
Regards,
TS