One of a small number of extremely fortunate Bowie fans from back in the day writes:
It was very cloak and dagger. Can’t remember exactly how I heard about it initially, but the procedure was that you had to attend a drum and bass gig run by Quadraphonic in The Kitchen nightclub [Clarence Hotel, Temple Bar, Dublin] a few days before, and find the person who would then give you a ticket (like the one above).
I did this, and went on my own, as no one else I knew seemed to grasp how important this was/. I spent a night in a small room with less than 200 people with free drink and food as Bowie and his band did a whole concert. I am extremely grateful to life now for providing this amazing experience.