In a preview of the new operatic version of Sondheim's Sweeney Todd, the lead actor's methodical approach is described:

For Mr. Delavan, preparing to portray so lethal a character has involved research into famous murderers, both historical and comparatively recent. He traces the roots of the work beyond the 1973 play by Christopher Bond (also called"Sweeney Todd, the Demon Barber of Fleet Street") that inspired Mr. Sondheim and his librettist, Hugh Wheeler; beyond"The String of Pearls," the 1848 play by George Dibdin-Pitt that inspired Mr. Bond; and even beyond the reports of a murderous barber who was hanged in London in 1802. For Mr. Delavan the roots of the story go all the way back to Sawney Bean, a 15th-century Scottish murderer and cannibal.

I'd always wondered about the historical roots of this particularly grisly drama. There's a Victorian music-hall song "Sweeney Todd, the Barber", which includes the immortal lines

He shouted out"Police!", nine times or ten
But no policeman came, it wasn't no wonder
Police weren't invented by then.

And of course cannibalism has always been fodder (sorry) for popular interest. But it's nice to see that the historical roots are being strengthened, rather than attenuated, in this revival.