Originally Posted by timnz
This is good old Mr. Collins, and he doesn't capitalize "world pro championship", as you did above. This term was applied to a number of different events including a minor stop in Cleveland and one in Oklahoma City! We need something more substantial than this.
Actually, Wembley was billed as the World Professional Indoor Tennis Championships, a self-proclaimed billing.
The key is "Indoor", which immediately reduces the prestige of the event.
There is no doubt from press coverage and player participation that the major pro events were held at the sites of the Slam tournaments, Wimbledon (1967 only), Forest Hills, Roland Garros, Kooyong.
These events carried the prestige.