You mentioned negative effects only, in response to my balanced and accurate view that immigration brings both benefits and problems.

I believe the same as you that we need to be choosey about who we let in, but sadly its not possible for us to do so to the extent I would like, as it would breach agreements we have as part of being in the EU, if we wish to control our borders ourselves, we need to leave the EU first.
Ironically part of the reason we joined the EU I believe was to lessen immigration by handing over control of our borders to europe as it meant we no longer had to honour agreements with african and indian nations that were part of the commonwealth, but at the time we joined the EU, we didnt realise the longer term effects of doing so as the EU itself continued to expand.