The Hunt for Britain’s Paedophiles is a three part BBC series which was first broadcast in 2002, the programme was controversial at the time due to its subject matter. The producer, Bob Long, followed specialist police teams as they work on attempting to infiltrate networks of child abusers.
One of the paedophiles featured in the series would go on to kill himself, and one of the production team needed counselling after exposure to some of the extreme things that they had witnessed. The series focuses on Operation Doorknock which led to the uncovering of a major underground child abuse ring which had been operating for over 30 years and abused hundreds of victims.
All three episodes are available to watch above (see tabs 1, 2 and 3). You may also find the Operation Ore series interesting, which includes footage of the arrest of The Who guitarist Pete Townshend.