Keith here http://www.statistics.gov.uk/cci/nugget.asp?ID=950 are figures apparently current to August 2009 from the ONS showing net migration still falling.

Those sucked into false predictions of prosperity (as in "The Grapes of Wrath") deserve our greatest sympathy, and for many reasons government (in its widest sense) needs to know who they are and where they are. Some may be illegal entrants, some may be overstayers, some may be failed asylum applicants, but not all are any such, I assert.

There is a case for removal of the above three categories (for they have been determined as not lawfully being here), and as I said long ago I believe it is possible for English law to make it clear that visa applicants can be detained during processing. That does not however enable full policing of removal.

Making rules about who is allowed to enter does not solve that puzzle.

Perhaps those who insist that population growth is ipso facto bad (a position I think irrational) or at present excessive (a position I think, allowing for projections, not justifiable) should set out: -

a) How they would reduce the excess of births over deaths, and
b) How they could find those unlawfully (now or in the future) here?
c) How they could prevent illegal entry?

There are no magic wands, and no government can be blamed for not achieving the impossible.