Two primary schools in north London have been subjected to “absolutely heartbreaking” late-night vandalism attacks that have left them with a security bill in excess of £200,000.Brunswick Park Primary and Nursery School has been targeted on four occasions and nearby Church Hill Primary School has been hit twice – most recently on Sunday night.The attackers, who used stones and a hammer to break dozens of windows, were caught on CCTV but their identities were disguised by balaclavas.