ISIS fanatics used the secretive messaging site Telegram to call for a “lone wolf” attack on Parliament just weeks before Khalid Masood struck.
A Sunday Mirror probe has uncovered chilling messages in which jihadi masterminds urged terrorists to mount atrocities in the UK.
They shared an image of an IS fighter dressed like executioner Jihadi John, wielding a sword in front of Big Ben.
The illustration – headlined Fight Them – showed a fireball and a tattered Union Flag flying from a pole.
Just weeks later Masood, 52, ploughed his car into scores of innocent bystanders on Westminster Bridge, killing three and injuring 50.