Richard
1 There has been a drop in net immigration this year, probably due to recession so probably temporary.
If down it is not unprecedented because it was bigger last year.
(Am I going too fast?)
It is still bigger than it was in the 50s or earlier..

2 If it is not discriminatory to say that there should be a limit, how can it be discriminatory to say if that limit has been exceeded?

3 I am not and do not defend BNP