You would not think it to see it now, but Ardbeg had a difficult time of it for much of the 20th century. The distillery was bought in a joint venture between Hiram Walker and DCL in 1959, both intending to supply their blends.
The subsequent years were very successful, but DCL backed out in 1979 (closing many of their other distilleries a few years later), and Hiram Walker then struggled in the 1980s era oversupply when interest is blended Scotch was waning. They closed it down for the majority of the decade. It re-opened briefly in the 1990s before being revived for good by Glenmorangie plc in 1997
The Ardbeg Twenty One was launched in late 2016, and is the first in a series of "Twenty Something" limited releases. The Twenty One does not have "Twenty Something" on the label, but it was loosely referred by name in the months before launch.