Calendar* Correction: 1970 National Jazz and Blues Festival

Several websites state that on August 6, 1970 Deep Purple, Yes, Cat Stevens, Black Sabbath and Wishbone Ash were among the acts at the 10th National Jazz, Blues and Pop Festival in Sussex, England, implying that they all played on that date.  While the Festival got underway on August 6, none of those acts performed on that day, as evidenced by the poster shown above.