Over the past few months there has been a concerted attack, from across the political spectrum, on the last Labour Government’s record on immigration. I was a Minister in that government. And I believe Labour has a record on immigration it can be proud of.

When I was told I was moving from Treasury to become Immigration and Asylum Minister, I was dismayed. I enjoyed the Treasury, and knew I’d now be on a hiding to nothing from both left and right.

Labour secured power without anticipating how immigration would come to dominate the political landscape. Being “tough on crime and tough on the causes of crime” were the Home Office priorities. This suited officials, who prefer criminal justice policy to the operational complexities of asylum and immigration.

The Home Office I joined wasn’t in a position to deal with these complexities. The Conservatives' new computer system proved an expensive failure, and voluntary redundancies in the Immigration and Nationality Department had created a backlog of over 50,000 cases. When I arrived I was told there were only fifty officials able to make decisions on asylum cases. Every month more applications were made than decisions given. Which isn’t a reflection on rank and file civil servants, many of whom were trying to do a very good job.

At that time asylum, not immigration, was the issue; and the debate was polarised.  Our duty was to grant refugee status for those with well founded cases, whilst returning those whose claims were unfounded. However, returns are easy in theory but complex, and often distressing, in practice. Passports are destroyed, countries refuse unsuccessful applicants, detention can be needed. And behind the statistics are individuals and families for whom Britain has become home.

There was, however, very little consideration of broader immigration policy. In my first few weeks I asked what that policy was. There was no definitive answer.

The preceding thirty years had seen no serious debate on immigration. The assumption behind the Immigration Act 1971 was that “primary immigration“ should be ended and migration was not a “political good”.

The opposite is true. At DTI and Treasury I saw how legal migration is, in an age of globalisation, an economic, social and cultural good.

People ignore it now, but by the autumn of 2000, Labour was starting to get to grips with the system. Asylum decisions now exceeded the number of applications and the backlog had fallen. That’s why, with Jack Straw's blessing, I chose to shift the terms of the debate.

Despite some nervousness from Number 10 and senior Ministers, I used an address to the IPPR to outline the enormous contribution migrants had made to the UK, to argue the case for managed migration and to float the idea of citizenship ceremonies. And it was that speech that framed our policy going into the 2001 Election, and beyond.

The case for migration is a compelling one. And it needs to be made. The OBR estimates current levels of migration boost GDP by 0.5 per cent. Current levels of population growth are no higher then they were in the early 1900s. And only just over one in 10 new jobs created in the UK goes to migrants, rather than British nationals. These are the facts about immigration, and they have to be pushed vigorously and consistently.

Of course mistakes were made, and some things could have been handled better. But it would be damaging if Labour’s current introspection about our election defeat led to the conclusion progressive migration policies must be abandoned.

On Saturday Ed Miliband told the Fabians that “High levels of migration were having huge effects on the lives of people in Britain - and too often those in power seemed not to accept this”.  And he has a point; we should have been much more upfront about the situation we faced, and placed it in a global context. But we were acutely aware of the difficulties posed by immigration, and were attempting to manage them in a fair but compassionate way.

There has been a remarkable reversal on this issue by some on the left. The aggressive rhetoric against “illiberal” policies has been replaced by the accusation we let down the white working-class. Suddenly it’s trendy to echo the rhetoric of Migrationwatch, who last week responded to a Daily Express report that “White Britons are now a minority in 4 towns and cities” by saying “This has happened as a direct result of Labour’s policy of mass migration which was foisted upon the country without any thought for the future effects”.

This is not sober analysis, it is the language of division. And it must be confronted, not “triangulated” away

Britain’s identity has, in part, been forged by the contribution of generations of migrants. That is an achievement to celebrate. And one of the achievements of the last Labour government.

Barbara Roche is the co-founder of Migration Matters, and former Immigration and Asylum Minister under Tony Blair