Phil Bowdery kept a unique souvenir from the first stadium gig he ever promoted. It was the opening UK date of Michael Jackson’s Bad tour at London’s Wembley Stadium in July 1988, staged by Barry Clayman Concerts (of which Bowdery was a director), and demand was unprecedented.

Applications for Jackson’s five Wembley shows that summer reputedly exceeded 1.5 million (in the pre-internet age, no less). But one ticket went unsold.

“I went to turnstile A and pulled out ticket 0001 ...