Build a great big wall around the festering turd pile that is the Isle of Sheppey, blow up the bridges, stick them all in the middle and let them get on with it Escape from New York style.
Solves the overcrowding problem, finally finds a use for Sheppey, which really really is a massive s h i t hole, and if you don't let the indiginous people of Sheppey on to the mainland, they can then shag each other to their seven fingered, inbred, overbite, pikey hearts content.
It is a win win win situation.
There's no argument against it, is there?