This should be Oho, shouldn't it? Unless "Dr Oho" is a "nickname" in its own right, like Doc Holliday or Dr. Who (Land of Fiction).
Talk about it here.
Dr Oho was a "minor celebrity", who was the adversary of a Master.
He was a tall, skinny man in his sixties with a gaunt face and a silver moustache, combed-back hair and blue eyes.
Dr Oho threw a party at his home in Maida Vale within a newborn Paul Magrs' dream, attended among others by Iris, and at the end of the night he took his most important guests away in a public call box. (PROSE: In the Sixties)
Behind the scenes
Dr Oho is clearly a pastiche of Dr. Who, the Second Doctor, and Peter Cushing, as Dr Oho blends together the abbreviated name and appearance of Dr. Who, the life of Peter Cushing, and the celebrity status of the Second Doctor from the TV Comics. His name is also a likely reference to the original Doctor Who title sequence, where the logo blurs and overlaps with a mirrored version of itself, appearing to read "DOCTOR OHO".