It was at Neil Young's Finsbury Park concert in London in 1993. I must have been no more than 10 metres away.
All in black, big hair, pointy shoes. It was definitely him. He asked me to join him, Neil and Pearl Jam backstage but I was too busy eating a vegi curry.
Maybe next time.
"Join the Cult of the Theremin / It's Velouriatastic!!"