My night with paedo hunters: This 54-year-old is accused of sending utterly revolting messages to a 'decoy' he believed was a child. But it was really a vigilante group - and I was there when they turned up on his doorstep, writes SUE REID

The knock on the door came in the early evening, at a housing estate in the Home Counties. Two hours later, the paedophile who answered was in a police cell - his name splashed over the internet.