Usually the convention is that a PPS who opposes a government motion resigns for the reason that technically they are part of the government, even though they are unpaid. The FT’s Westminster blog lists ten PPS who have signed the EDM opposing Mandelson’s plans to make the Royal Mail pay:

David Wright (PPS to John Hutton), David Anderson (Bill Rammell), Claire Curtis-Thomas (Baroness Scotland of Asthal), David Hamilton (Ed Miliband), Mark Hendrick (Jack Straw), Stephen Hesford (Vera Baird), Sharon Hodgson (Dawn Primarolo), Ashok Kumar (Hilary Benn), John Mann (Tessa Jowell), Stephen Pound (Stephen Timms)

Laura Moffatt is a former PPS to Alan Johnson, her opposition might be a sign of where he really stands. Nick Brown, Gordon’s long time henchman and now chief whip is also said to be not keen mon the bill. It is getting a bit like the dying days of the Major regime when euro-sceptics openly defied the government…