Gary Mawson’s selfish and sick desires led him to target teenage girls and a young woman in a series of incidents described by police as “escalating”.

He began by stalking his victims and exposing himself to them but, on the final occasion before his arrest, went further, sexually assaulting a girl of 14.

Such outrages would have been frightening enough but the fact that he chose, on occasion, to hide his identity with a Halloween mask adds a chilling dimension to his crimes.

It is the stuff of nightmares, and the impact on his victims has been considerable, the incidents causing them significant distress.

After he was arrested he even told police they had caught him at the right time because he was a danger to young girls.

Any right-thinking person will be truly disgusted at these offences and we have no doubt that many readers would have been happy to see him locked up for considerably longer than the four years he is set to serve.

Certainly there would have been no complaints if that had been the case.

But now that sentence has been passed we can only hope that he gets treatment for his appalling urges and addresses his depraved behaviour.

More importantly, when he is finally released it is imperative that he is properly monitored so that he is never able to blight the lives of anyone again.

That is no doubt the intention and it must be followed through.