A400M was once Future Large Aircraft (FLA); FLA was supposed to repace all large a/c. That proved unfeasible, so the tanker/transport requirement became Future Strategic Tanker Aircraft (FSTA) and another fight arose between A400M and C130J as the Future Transport Aircraft (FTA). FSTA then became a Private Finance Initiative (PFI) project; the preferred platform became the A330 Multi-Role Tanker Transport (MRTT) offered to the rental Air Force (rAF) by AirTanker. Meanwhile, A400M which had been the FLA was given the go-ahead to be the FTA; however, to fill the gap, a Short Term Strategic Airlifter, STSA, was needed and that became a fight between the An124 and the C-17. The rAF decided upon leased C-17s as STSA to fill the gap before FTA became reality; however, the C-17s will now be bought and the STSA will become another FTA, but not the sole FTA as that will still be the A400M. Which, of course had once been FLA and rejected as FSTA. Nevertheless, the Common Standard Aircraft (CSA)A400M does have a requirement to have an AAR role, but not as a strategic tanker as that will be the job of the FSTA, presumably the A330 MRTT.... Although there is, of course, the A310 MRTT in service with other countries but not offered by any of the FSTA bidders even though it had been studied under an earlier project by MoD Department of Future Systems as it then was...
C-17 which was the STSA but wasn't an FSTA will be an FTA.
A400M which was FLA, then rejected as FSTA will become the 'official' FTA.
A330 MRTT will probably be the FSTA under a PFI project.
Oh - and ASTOR is well under way.