The prospect of an amnesty for illegal immigrants has been raised by the new minister in charge of immigration.
Liam Byrne told MPs he had asked for a report on the issues around a possible amnesty, saying it was "too early" to rule out the controversial idea.
So should there be an amnesty - or would it be a disaster?
KEITH BEST, IMMIGRATION ADVISORY SERVICE
We have been advocating an amnesty for a long time. It should happen at the same time as the introduction of the government's e-borders programme [a computerised system for recording arrivals and departures from the UK] between 2007 and 2008 because it would help to clear the decks.
If we held an amnesty at this time, it would allow us to know, once and for all, the identity of those who have over-stayed while encouraging people to come forward.
But it has to be done right in order to work.
It has got to be on the basis that if an illegal migrant can show that they have been in stable employment for some time, are still in employment and have committed no crimes, then they should be given leave to remain in the UK for a specified period.
That would be the way to do it because you would then know who they are.
I think what the government is doing by raising this issue is seeing what reaction there will be from the newspapers.
If there is a neutral response, I think they will go ahead with something along these lines.
The established argument against an amnesty is that if you offer one, then more people will only come into the UK in the hope of being able to benefit from it
This is why an amnesty has got to be tied to the e-borders plan in order to work. But in general, there are often suggestions and analysis that potential migrants are deterred or influenced by such policy changes. The reality is that people come from many, many different places.
I don't think that the potential asylum applicant in Kurdistan has been reading Hansard and is aware of the deterrents against arriving - it's simply not what they are told to expect.
They expect to find jobs, which is why economies not doing as well as ours, such as France and Germany, simply do not experience this.
The best way to make illegal migrants legal is to ensure that they have means to work legally.
If you further open up the routes that people can use to come to the UK to seek work you stop people coming in on the back of trucks while, at the same time, starving the people smugglers.
SIR ANDREW GREEN, MIGRATIONWATCH UK
Granting an amnesty would be extremely expensive as it would lead to full access to the welfare state to people who have been living and working illegally in the UK, including housing, health, pensions and job seekers' allowance.
France: 152,000 (1998)
Greece: 397,000 (1998)
Italy: 308,000 (1998)
Spain: 700,000 (2005)
Source: Individual governments. Figures refer to illegal immigrants given form of residency.
It would only be worth doing if it solved the problem. But an amnesty achieves nothing because this group of illegal immigrants would be replaced by another group.
Italy has had five amnesties in the last 20 years and Spain has had six. Each time, there have been more illegal immigrants - now having reached 700,000 in Spain's case. It's worked to attract people to those countries.
At the root of the problem however are unscrupulous employers [in the UK]. As long as people are prepared to employ someone on very low wages, in poor conditions, you will have a problem because people will come and work.
They will come and live here several to a room so they can still save up money to send home. You have to target the employers with penalties.
There are now laws for on-the-spot fines of £2,000 for being found employing someone illegally, rising to £5,000 if you are found knowingly doing so.
If these were properly implemented then people would drift home.
We don't accept the argument that there would be a substantial tax benefit from an amnesty because the figures that were produced recently [in a think tank report] did not take into account the added costs on the welfare state.
The only alternative is to close off the market for illegal working. Prices and wages would go up but I cannot understand why the unions [some of whom support an amnesty] object to this.
Anything that raises wages for the very low-paid would surely be a good thing - it would also prompt employers to consider how to improve their labour productivity.
If you give an amnesty tomorrow, people can still come into the UK on the back of a truck or as a student over-staying a visa and get illegal work for £4 an hour or less.