Lou Thesz appeared in Toronto many times from the 30's to the 60's and listed Frank Tunney as one of his favorite Promoters in several interviews given over the years. He not only lost the NWA Title here twice (to Whipper in '56. Dick Hutton in '57) and won it once (Rogers in '63) but also successfully defended the belt a total of 29 times between 1949 and 1965. He would also challenge for the belt in Toronto another 4 times before making his last appearance for Tunney in 1969.
The pic above of Thesz walking the ramp at MLG is from his final year at MLG - 1969
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Curious was Thesz returning to Toronto in 1976 to work on George Cannon's attempt to go head to head with Tunney. Cannon's show at the CNE Coliseum drew only 600 vs Tunney's 40th Anniversary show at MLG which drew 7,000. That story can be found in an old KM column here
Clip from Oct 10 1963
Stats from Gary Will's research