Letter to almost 300,000 parishes warns of blaming immigrants for ills of society . Cardinal Vincent Nichols , the Archbishop of Westminster , voices concern . Insists parts of Britain would 'grind to a halt ' without immigrants . Most who come to UK 'work hard and make a very positive contribution ' Cameron 's pledge to cut migration in tatters after figure hit 500,000 .
Letter to 500,000 parishes warns of blaming immigrants for ills of society . Cardinal Vincent Nichols , the Archbishop of Westminster , voices concern . Insists parts of Britain would 'grind to a halt ' without immigrants . Most who come to UK 'work hard and make a very positive contribution ' Cameron 's pledge to cut migration in tatters after figure hit almost 300,000 .