What was the name of Jack Stapleton's school?

Mr. Stapleton taught at St. Oliver's school. Note, he taught there under a different name.

“I have come prepared to do so,” said Holmes, drawing several papers from his pocket. “Here is a photograph of the couple taken in York four years ago. It is indorsed ‘Mr. and Mrs. Vandeleur,’ but you will have no difficulty in recognizing him, and her also, if you know her by sight. Here are three written descriptions by trustworthy witnesses of Mr. and Mrs. Vandeleur, who at that time kept St. Oliver’s private school. Read them and see if you can doubt the identity of these people.”