Last night, Bayreuth Opera streamed Wagner live over the internet for the first time - a sign of the times, as opera houses leap into the future with HD cinema screenings and web downloads.

It used to be so simple. In the old days, if you couldn't get to see opera on stage, you waited a few months for the telly to broadcast one. The sound may have been boxy and the picture small, but the performance came free to every licence-holder's home at the flick of a switch.

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