In the latest Labour anti-terror initiative, huge numbers of staff on rail networks, at airports, shopping centres, public buildings and sports venues have been picked out by MI5 and the police to be taught how to watch for 'suspicious behaviour' and respond swiftly in the event of an atrocity.
The Home Office plans are likely to raise questions over the effectiveness of an army of amateur 'terrorist-watchers'.
There are fears they will swamp the police and security services with spurious alerts or single out law-abiding British Muslims, which could also inflame religious tensions.
Citing security grounds, the Home Office would not provide details of the training, which MI5 helped to draw up, beyond that it centred on improved vigilance and response to terrorist attacks, including evacuation and crowd-control procedures.
Writing in a Sunday newspaper, the Prime Minister said the public 'should be under no illusion' that 'the biggest security threat to our country and other countries is the murderous agents of hate that work under the banner of Al Qaeda'.