So it seems I was right near the end of the game then. Like, 30 minutes from it. Had to chase after Jack all over the place, being attacked by hordes of baddies on the way. Luckily, there were plenty of other heroes and guards and stuff around to take them on, so I just ran past them all. Eventually, I ended up at the Hall of Fate back in the Guild for the final showdown. Which was disarmingly easy. Chose not to keep the Sword (and kill my sister), and instead threw it into a vortex.
With the half-hour long credits sequence out of the way (which also listed the 50 or so babies born to Fable staff during the game production, amongst other things), I carried on playing for a bit. I did a few jobs for Lady Grey, found her necklace, beat Thunder for her cold heart, and married her (three wives now!), but now I don’t know what to do. Treguard keeps telling me to “check the Guild for more quests”, but when I get there it’s all blocked off and there are no quests to be had. I can’t even “select” the big Quest Map in the Guild foyer. Wandered round Albion for a bit, but I seem to have run out of interesting things to do. THE END then.