A fellow researcher contacted me with the following question -
Who and when were the first rock'n'roll/pop band to play at the City Hall?
He had found that Buddy Holly and the Crickets played there on March 4th 1958 but asked if I knew of an act before that?
After a bit of delving around, and the help of the excellent Sheffield History Forum, it was a bit of a surprise when we found the answer
According to the listing, Nat King Cole preceded Johnnie Ray by a few days in April 1954, and he was preceded by another jazz singer Sarah Vaughan in 1953.
Johnnie Ray was the first "rock n roll" singer to play there on 19th April 1954.