IN HER article on immigration Minette Marrin (Comment, last week) is correct to argue that numbers matter. If migration continues at the 2004 rate (the latest year for which statistics are available) then by 2051 there will be a net outflow of 5.8m British-born individuals and a net inflow of 15.8m foreign-born individuals. Taking into account the children born to migrants, the combined effect of these flows will be to add another 16m to the British population by 2051.

Such a rapid transformation of British society through migration is without precedent since the Danish and Anglo-Saxon settlements which took place more than a thousand years ago. It may be that mass immigration is a good thing for Britain, or maybe not.

Either way, we need a serious and informed debate on the issue. Yet only a handful of respectable politicians will even discuss the issue.

Professor Robert Rowthorn
Faculty of Economics Cambridge

OF BENEFIT TO ALL: I mostly agree with your editorial on immigration (Welcome, up to a point, July 23), but it is rather glib to assume that just because there are a reasonable number of jobs for migrants coming from Poland, and probably shortly Romania and Bulgaria, that this will continue to be the case.

In the event of a recession (not unlikely considering the current global situation) there is real danger that many of these migrants could become jobless and start claiming benefits. In a high unemployment climate resentment would rise among native British workers and social unrest becomes a possibility.

Add the implications for housing, education and healthcare of large-scale immigration and it really is time for a much longer-term perspective to be taken on this issue.