Here’s an ad from the September 16 1946 edition of the Toronto Globe and Mail for Blackstone, the magician:

Company of 30 – mostly girls!
Harry Blackstone Sr. (1885-1965) was one of the last of the old-school breed of magicians who performed in white tie and tails. He was arguably at the peak of his career in the 1940s, as a comic book and a radio series were created in that decade that featured him. His son, Harry Jr., also became a magician.
YouTube has footage of him performing in 1956 (though the sound quality is poor), along with this commercial for Post cereals.