Cursed, or perhaps blessed, with almost no visual memory at all, I had almost completely forgotten what the Royal Opera’s current Tannhäuser, directed by Tim Albery and with set designs by Michael Levine, looks like. Or perhaps it was the natural tendency to repress the memory of unpleasant experiences. Wanting to enjoy the Overture, I closed my eyes until the moment the Venusberg ballet that Wagner composed for the doomed Paris version in 1861 began.