The political leaders have known this trajectory, it is no secret. Muslim behavior/terrorism correlated with percent of population:At 2% and 3% they begin to proselytize from other ethnic minorities and disaffected groups with major recruiting from the jails and among street gangs.
From 5% on they exercise an inordinate influence in proportion to their percentage of the population.
When Muslims reach 10% of the population, they will increase lawlessness as a means of complaint about their conditions
After reaching 20% expect hair-trigger rioting, jihad militia formations, sporadic killings and church and synagogue burning
At 40% you will find widespread massacres, chronic terror attacks and ongoing militia warfare
From 60% you may expect unfettered persecution of non-believers and other religions, sporadic ethnic cleansing (genocide), use of Sharia Law as a weapon and Jizya, the tax placed on infidels
After 80% expect State run ethnic cleansing and genocide.
http://www.freerepublic.com/focus/f-news/3557861/posts?page=6#6
England/Wales: 5.4%
London: 12.4%
Manchester: 15.8%
Birmingham: 26.9%