Tom Baldwin is a former political correspondent at The Times, who served as the paper's Washington correspondent for four years before returning to London as chief reporter last year.
He is a friend of Alastair Campbell and was seen by some as Campbell's mouthpiece when Blair was in power.
A tenacious scoop-gatherer with Labour loyalties, his appointment has been largely welcomed by party insiders who are keen to see their new leader land a few blows upon David Cameron.
Labour's political rivals have been less kind about the appointment.
Tim Montgomerie, editor of the ConservativeHome website, wrote this week: 'I had two experiences of Mr Baldwin and on both occasions he wasn't interested in the truth, just attack journalism. Politics is going to get nasty with him at Ed Miliband's side.'
Bob Roberts, political editor of the Daily Mirror, is a far less divisive figure. According to one fellow lobby journalist on a rival newspaper: 'Bob's popular and he'll be good as he understands what makes a story in different papers - he knows how Ed can get a good show in the Mail as well as the Mirror.'
Before joining the Mirror, Roberts was deputy political editor at the Press Association.