One of Labour's great achievements under Ed Miliband has been to encourage an open and transparent debate about our future while avoiding the kind of destructive infighting which characterised the party's behaviour the last time we lost office in 1979.
I'm really proud of the many great things the government in which Michael Meacher served for six years under Tony Blair did to rebuild our public services, fight poverty and make Britain a fairer, more equal country.
That is why I find it so disappointing that Michael has chosen to align himself  with the small hard left minority of the party that seem intent on attacking Progress and reigniting the kind of divisive, factional warfare which, as Michael well knows, was so damaging to Labour in the early 1980s.
We really cannot return to the days where conversations within the Labour party become more important than our conversations with the electorate. I cannot, however, allow the criticisms of Progress to go unanswered. In his piece, Michael refers to "detailed recent investigations" into the organisation. I am afraid he is being rather coy here. The document to which Michael links was, in fact, an anonymous dossier posted to constituency party secretaries and councillors at their home addresses over recent weeks.
It is a great shame that time and money which could have been used attacking the Tories and helping Labour to develop an election-winning agenda was instead deployed producing and mailing a document which contains multiple inaccuracies and gross misrepresentations.
But equally disappointing is the fact that the author of that document chose to hide behind a cloak of anonymity and that Michael decided to repeat charges which Progress had already comprehensively answered .
One of the most refreshing things about Ed's leadership of the party has been his total intolerance of the kind of anonymous briefings which proved so damaging to Labour during our last years in government. We must not allow such tactics to resume.
Another hallmark of Ed's leadership which I hoped Michael would have joined the rest of the party in welcoming is the encouragement of pluralism and free and open debate within Labour's ranks. There are many points of view within the party with which I profoundly disagree. However, I have always believed that, as a party, we are strengthened by all those who are genuinely committed to the election of a future Labour government having their say. That's why I welcome Compass's place within the party and why we have held joint events with them and co-operated where we have common goals.
In my experience, playing the ball and not the man is always preferable in politics. I would, therefore, encourage Progress's critics to join us in a comradely debate about ideas, rather than trying to delegitimise those with whom they disagree. It is a shame, therefore, that there is not one mention in Michael's piece of The Purple Book , described by the Guardian as "the first concerted attempt to set out a new agenda for Labour", which Progress published last year.
I notice, too, that Michael appears determined to suggest that Progress is somehow antipathetic to the leadership of the party. This is a somewhat strange charge to make of an organisation of which Ed was, until the general election, a vice chair and which will welcome him as the keynote speaker at its annual conference  for the second year running this May. More broadly, I'm really pleased that already this year we have had members of the shadow cabinet like Rachel Reeves, Douglas Alexander, Chuka Umunna, Liam Byrne, Jon Trickett, Ivan Lewis, Sadiq Khan, Stewart Wood, Liz Kendall and Peter Hain, speaking at the events  Progress has been organising to debate the new centre-ground that Ed described at conference last September.
I am grateful that, despite the strenuous efforts of some to paint Progress as a "party within a party", Michael recognises the utter ridiculousness of comparisons with Militant. I hope, too, that on reflection he will see that it is Progress's opponents, with their intolerance of views with which they disagree, continual questioning of people's motives and apparent desire to collapse Labour's big tent, who are the real heirs to Militant.
As for Progress, we will not be distracted from our task, which is to work flat out to secure a Labour victory under Ed Miliband's leadership at the next general election. We will contribute ideas to Labour's policy debates - some will no doubt be accepted, while others will not. However, Progress is not simply a magazine. It is also a campaigning organisation. So we will continue to organise campaign sessions for Labour up and down the country. Labour is stronger for being a broad church, both organisationally and ideologically. Let's keep it that way.
Robert Philpot is director of Progress