If there is one thing Margaret Thatcher liked it was a good argument; and if there was one place where she felt those arguments should be held, it was in the House of Commons.

So whilst it is right and proper that MPs pay genuine respect to her strengths and achievements in Parliament today, and express sadness at her passing, it would be wholly wrong if MPs who disagreed with her policies and the impact of them upon their constituents and the wider world felt unable to say so.

There is something very peculiar about death in Britain. I heard the news of Mrs Thatcher’s demise in Scotland, and then spent several hours driving south listening to hour upon hour of glowing tribute. Colleagues of hers who, when I was a journalist, would happily confide how much she made their blood boil, queued to say how marvellous she was. Those who helped bring her down because she had become hugely unpopular with the public – the fact she was forced from office seems to have been little mentioned in the last two days – rushed to tell us how amazingly popular and in tune with public opinion she had been.

Nobody should speak ill of the dead, and the parties and dancing in the streets were offensive and misplaced. But nor should anyone condone hypocrisy, and hypocrisy comes when people say not what they believe, but what they believe they ought to say.

Partly this is about form, and about necessary respect for a dead person and that person’s family. But when it comes to political figures as important as Margaret Thatcher, I think there should be more balance in the assessment than has so far been coming through the media. Just as she liked a good argument, so she disliked hypocrisy, and it would do the Commons and her memory no good if today MP upon MP lined up merely to say how marvellous she was.

Of course, as a Conservative Prime Minister, David Cameron will and indeed should emphasise her strengths and achievements, and laud her memory for all it is worth. As Labour leader, Ed Miliband – who got the tone right on the day her death was announced – has perhaps a trickier task. He has to do all that too, but he must also reflect the reality that she was a divisive figure, and that her legacy is far from being an unalloyed success.

And frankly, if Parliament is to mean anything, on a day like today, MPs should not just be allowed, but should be expected, to say what they think, without the Tory and/or right-wing media hysteria that may emerge if they do not go along with the mood of the moment.

Many of my memories of her come from my time as a journalist covering her rise and fall. She was elected as I sat my finals at university. By the time she was gone I was political editor of the Daily Mirror, and in between times, I had followed her around the world, written about her with all the passion I could muster, working for a paper whose editorial line, in common with my own views, opposed so much of what she did. But as I said on Monday, she was one hell of a story to work on, and she was also one of the few real change Prime Ministers.

So yes she is a huge historic figure. And precisely because of that, even as the funeral is still being planned, there should be a proper and not sentimental debate about her.

There is a lesson for Labour in the broadly positive media and political response to her death. Tories never tire of talking up their past. This is not an act of vanity, but strategy. To have a generation unborn at the time of the Winter of Discontent still vaguely aware of it speaks volumes for the Conservative Party’s disciplined use of history as a political tool. To have a young generation today being bombarded with messages about how marvellous she was is good for the Conservative Party tomorrow; and they know it.

Labour, by contrast, has a habit of running down its own past and its own history. We have seen too much of that in recent years. Tony Blair won three elections, presided over the peace process in Northern Ireland, helped rid the world of murderous dictators like Saddam Hussein and Slobodan Milosevic, saved our schools and hospitals from remorseless decline under the Tories, delivered devolution, the minimum wage, ten years of growth and prosperity, Bank of England independence, Sure Start, on and on I could go. Yet to hear a lot of Labour figures, and the media echo chamber, his record was a negative one.

Margaret Thatcher was capable of making life difficult for her successors. But they never stopped talking her up. Partly because they felt she deserved it. But also because it was good for them.

I know I am not alone in being unsettled by the scale of the funeral arrangements, and, following on from the snub to Labour Prime Ministers at the wedding of William and Kate, the Royal presence. The Royals represent and embody the State. Politicians represent their parties and some get to lead their country. The case for a State funeral for Winston Churchill did not even need to be made. There is not a person alive who does not believe he helped to save the UK. But Margaret Thatcher’s role and record is not so clear.

David Cameron says she ‘saved the economy.’ But for many parts of Britain, people and communities feel she destroyed it, and abandoned families in her wake.

Yes, she can point to a historic role in saving the Falklands from Argentina, and even more significantly in working with Ronald Reagan and Mikhail Gorbachev to end the Cold War and bring down the Berlin Wall. But her role in defending dictators like Pinochet, and her support for the apartheid regime in South Africa, deny her the right to be free from criticism on the foreign policy front. And some of that criticism, amid all the respect and sadness, must surely be heard in the Commons today.

I mentioned I was in Scotland when I heard she had died. Later that day, I was in Manchester for the football. There was quite a dissonance between the mood and reaction on the airwaves, and the things people were saying, the memories they were recalling, in those places. They are part of history too, and their anger and criticisms should not be airbrushed from it.

There is one other point I want to make. Yes, she was the dominant figure of her generation. Yes, Tony Blair shifted the Labour Party to the centre in part as a response to the success of her politics. And she may well have said, on being asked what her greatest success was, ‘Tony Blair.’ But she would never have devolved power to Scotland, (remember the poll tax?) brought in the minimum wage, taken the risks (and yes I understand why she hated the Republicans) needed to bring peace to Northern Ireland, etc etc. Tony once made a speech acknowledging her strengths and some of the necessary changes to Britain that she made. But he said too that she paid insufficient regard to the social consequences of her economic policies, that she did not invest sufficiently in schools and hospitals, and had a misguided and muddled approach on Europe. All true.

He hugely admired her strength. ‘God she is so strong,’ I recorded him saying in my diaries after one of her visits to see him in Downing Street. But a lot of what Labour did was to repair the impact of Thatcherism, not build upon it.

And if the Tory leaders who have followed her were being totally honest, they would admit there have been times when she has been their problem, not their solution. Remember that David Cameron felt he had to run not as the heir to Thatcher, but the heir to Blair, and indeed felt he had to invent the idea of The Big Society as a direct antidote to her – admittedly often misquoted – line that there is ‘no such thing as a society.’

So I stand by the only thing I have said so far – a short tweet on Monday, saying she was a great politician to follow as a journalist, and a real change PM (a tweet, incidentally, which led to me getting a fair bit of abuse from those who felt I was being too soft and soppy.)

But I do not resile from the many harsh words I wrote about her as a journalist, nor the way that we used her unpopularity, and her impact upon successive Tory leaders, to win three elections. Remember the poster that helped do for William Hague. A picture of him with Margaret Thatcher’s hair and a slogan … ‘vote Labour on Thursday, or they get in.’ It worked because whatever good Thatcherism did, it did a lot of bad too, and people did not want it back.

I respect Margaret Thatcher enormously as someone who knew what she believed and fought tirelessly to put those beliefs into action, through a life of public service. But it does her memory no good for any of us, least of all the MPs who speak today, to pretend there is only one side to the Thatcher story. Parliament should pay proper respect today. But all sides of that story should be told.