A number of celebrities have signed an open letter to British prime minister David Cameron warning that “a diminished BBC would simply mean a diminished Britain. Daniel Craig , Rachel Weisz , Judi Dench , J.K. Rowling and Stephen Fry are among those who signed the letter, which was published in various newspapers. The celebrities also oppose turning the U.K. public broadcaster into what they called “a narrowly-focused market-failure broadcaster.” Doctor Who and Sherlock showrunner Steven Moffat, talk show host Graham Norton, Michael Palin, David Attenborough and TV chef Jamie Oliver are also among the signatories. The letter was published ahead of the presentation of a “green paper” by the U.K. government on Thursday that will provide first thoughts on potential changes to the BBC mandate and reforms.