http://news.sky.com/story/1332194/luton-airport-evacuated-flights-diverted
Sky News sources say the alert is thought to have been sparked by a checked-in suitcase that was picked up by a security scanner.
here is a link ... http://www.itv.com/news/london/update/2014-09-08/luton-security-alert-may-be-linked-to-x-ray-machine/