But despite Scotland Yard initially describing the claims as "credible and true", a subsequent investigation by the Northumbria Force had found his "most heinous" allegations were "totally unfounded" and "hopelessly compromised".
The barrister said: "These child sex offences were committed whilst he was speaking to investigating police officers. At the same time he perpetrated these lies about Harvey Proctor and so many others, he was also viewing indecent images of the gravest kind and spying on small boys".
The jury was told that when confronted with the evidence Mr Beech had initially pleaded not guilty, even suggesting that his son might have been responsible for the material.
But just as the trial had been about to get going in January he had changed his plea and admitted the offences.
The prosecutor said: "This evidence demonstrates that Carl Beech is a committed and manipulative paedophile, capable of deceit to investigators and limitless manipulation when required, including if necessary, framing his own child.
Mr Badenoch suggested it was Mr Beech’s interest in child pornography that had prompted him to go to the police with his own allegations in the first place.