Black Sabbath missing gig from 1972?

My brother and I went to buy tickets for Pink Floyd, but at 8.30am the queue stretched from Wilson Peck’s almost up to the City Hall, so instead, we joined the much shorter queue for Sabbath, who were due to play the City Hall on 08/02/72. However, it was then cancelled due to Ozzy Osbourne’s “illness” (can’t imagine what that could have been!) and rescheduled for February 21, 1972, according to the letter we had. The rescheduled date appears on several online Sabbath gig archives.

However, we’re certain that this gig did not take place, certainly we never saw them that year. I can’t find my ticket and can only assume it was exchanged for a refund at the time. Can anyone clear up this mystery?