This country is a very small land mass and can only support a limited population.I would suggest 50 million max. Housing is too expensive,road are congested,all basic utilities are overstreched to the point of breaking down. We are approaching a time when water rationing will be introduced as a permanent fixture( design standards have already ben lowered to a figure of 125 ltrs per person per day) The more building deveopment we allow the less agricultural land is available for food. We then have to import more than we do now with the increased carbon footprint and increased financial cost to the consumer.
There is of course one other major issue and that is birth rates. Foreign nationals appear to produce far more offspring than the indigenous Anglo SaxonCelt.We are in danger of wiping out the white british race.