Professor Ledbury is a member of the last tour among the Pilgrim Parties in Dark Lord of Derkholm. He is on the tour with his sister, the formidable and pigheaded Miss Ledbury, she of the endless notetaking and overbearing personality.
The professor, from the beginning of the tour, is self-effacing and vague, as if his memory is just about gone. He also begins the tour looking pretty frail, but seems to gain strength and mental acuity as things progress.
His specialty, when he was on Mr. Chesney's planet, appeared to be advising Mr. Chesney on the magical creatures in Derk's world. The professor was the one who told Mr. Chesney how much gold the dragon folk needed to survive, although later he pointed out to everyone that he'd said at the time that it was only a guess.
The one thing that always seems to fascinate him is the appearance of wizard Derk's crew of Dark Elves, led by elvish Prince Talithan. The professor becomes more than usually melancholy each time the elves appear and then disappear.
And there is more to Professor Ledbury than meets the eye.