They used to have Glenlivet in addition to the Dewar's. But Glenlivet apparently stopped making mini's (all the airlines dropped them around the same time).
That's the line all three US majors have offered up, but it's not true. BA still has The Glenlivet minis, both a non-age-disclosed version in economy and a 15-year old in business. My solution to make Dewars drinkable is to bring a miniature of my own filled with a peaty Islay single malt, adding about a third of that bottle to each glass (mini) of Dewars. Adds a bit of character.