Main Harry Potter star Daniel Radcliffe had appeared naked in Broadway and London productions of the psychological thriller play Equus.
"Well, this is awkward. Sorry, Jo..." Lewis responded, using Rowling's nickname.
".@Mattdavelewis I will always support you whatever you want to do, Matthew," she said. "Now go put some clothes on."
Then, gloriously, Jason Isaacs, who played the evil Lucius Malfoy, got involved.
"Surely Neville Pertbottom now?" he tweeted.
".@jasonsfolly @Mattdavelewis I wouldn't know," Rowling replied. "I hastily averted my eyes and read an article on Political Correctness to get over the shock."
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