I had two bottles of the '97 vintage of this beer earlier this year, which were not primed, and even after 12 years the amount of carbonation in the bottle was exceptionally low. The '08 vintage has been primed however, but at a very low level (16g in 9L) . . . the other issue is that as its a 10%abv beer the yeast is pretty knackered and possibly not able to carbonate . . . So you also have to reseed with fresh yeast as well. . . . I used 0.1g/l . . . That was bottled in January and I am yet to taste any, it won't really be ready for drinking until Christmas this year, and will probably be at its best around 2015/2016.