Dr. Stewart is an Archaeologist and Egyptologist, based at the Cairo Museum of Antiquities. He has liased with Robert Carstairs on more than one occasion, and has had connections with the Ripper organisation indirectly through Peter Davis, an American Ripper who was driven insane while searching for the 'Ankh of Set' in Egypt.
He is, first and foremost, an academic, and an expert in the deciphering of heiroglyphs. He has moderate experience in the field and has good contacts in the area around Cairo with various outfitters and bands of diggers, enabling him to put together an expedition in reasonably short order if required.
He is invariably accompanied by his research assistant Daphne Monroe.
It transpired that he was, in fact, a servant of the Cabal who wished to usher in a new age of Egyptian rule, with himself becoming a living mummy and part of the ruling elite. He was slain during a ritual that would have made him and immortal, preventing him from becoming a great threat to the people of Egypt and beyond.