When Maxwell acquired IPC's comics division in 1987, it acquired the rights to all new material published from sometime in 1969 onwards. This specifically included all rights to Dan Dare ever, IIRC.
When Egmont (as it became) acquired the comics division from Maxwell's heirs, all those rights subsequently passed to Egmont - effective October 1991, again IIRC.
When AOL acquired IPC, it did not acquire the likes of Action, Battle and other post 1968 IPC comics - these had already gone to Maxwell and then on to Egmont.
Rebellion acquired 2000 AD, the Judge Dredd Megazine and all character created for those titles - excluding obvious creator-owned strips like Big Dave, Button Man et al, and other things like Urban Strike, A Life Less Ordinary and the like which ownership belonged to other companies.
Egmont had already sold all rights to Dan Dare by the time Rebellion acquired 2000 AD etc, circa July 2000.
So, Egmont holds the rights to Battle and Action - although some would argue that the method by which IPC first acquired the rights in that material might be worth contesting legally. In reality, unless those rights become worth possessing (say, somebody did a Charley's War movie, for instance), nobody seems in a rush to contest them.
In essence, a Battle Action special is possible. Indeed, Egmont Roy of the Rovers monthly reprinted Action football strips in the mid-90s.
Egmont holds the rights - no Rebellion, nor AOL Time Warner.
