Every national newspaper editor has backed the Press Gazette Save Our Sources campaign and signed a joint letter of protest to Prime Minister David Cameron over police spying on journalists' phone records.

Around 100 editors have signed a letter co-ordinated by Press Gazette and the Society of Editors to warn that the draft code of practice on use of the Regulation of Investigatory Powers Act puts journalists' sources at risk.

Politicians promised new controls in the code, but instead the new draft guidance states that police can continue to secretly view journalists' phone records provided they give “special consideration” to the “proportionality” of doing so.