A 51-year-old man has been sentenced to eight years in prison for 21 counts of various sexual offences against a number of teenage girls from all over the UK.

Jason Armstrong, who is originally from Sheringham, Norfolk, but most recently resided in Moorends, Doncaster, appeared at Sheffield Crown Court via video link from prison where he has been on remand, to be sentenced after previously entering guilty pleas to all of the offences at court.

Armstrong pleaded guilty to nine counts of sexual activity with a child, two counts of meeting a child following sexual grooming, two counts of inciting a child to engage in sexual activity, three counts of distributing images and videos, four counts of making indecent images of children and one count of facilitating the commission of a child sex offence.

The offences were against seven victims, aged between 15 and 17-years old, from Cleveland, Cheshire, Berkshire, North and West Yorkshire and Scotland.

South Yorkshire Police began an investigation into Armstrong after receiving a report in 2016 that he had been using a fake profile on social media and through messaging apps, to pose as a 16-year-old female to 'make friends' and gain the trust of vulnerable teenage girls, and then ultimately going on to introduce himself as Jay, a 'friend' of this fake persona.

Detective Inspector Richard Partridge investigating said: 'Armstrong is a prolific offender who intentionally and continually sought out and targeted young girls by using different online platforms and fake personas to build relationships with them.

'This was all abhorrently calculated and planned; he preyed on his victims by lying about his persona and age to gain their trust, to then groom and incite sexual activity with them for his own disturbing and sick sexual gratification.

'I am pleased he is now behind bars for his perverse actions and I can only hope this offers some form of solace to the victims, who I would I like to praise and give thanks to for their strength and bravery throughout the investigation.'

Following the initial report, Armstrong was arrested by SYP and a search of his home and car was conducted, identifying a number of mobile phones and electrical items he had used to contact, and in some cases used in arranging to meet victims.

Following the seizure of these items, a long and complex investigation ensued which led to the identification of victims across the country. Although Armstrong resided in Doncaster, this was for a relatively short period of time and the vast majority of his offending was national and not believed to be within the South Yorkshire area.

DI Partridge added: 'This has been a lengthy and multifaceted investigation and I want to acknowledge and thank all the officers who gathered comprehensive information and extensive evidence to build a strong case against Armstrong, as well as our partner agencies who have provided support to the victims and assisted us in putting measures in place to aid their protection and safeguarding of them.

'This case highlights the importance of being safe online and I would encourage anyone who has any concerns over the identity of a person, or would like to report any instances of inappropriate or illegal activity, to please contact police. We will do all we can to stop sexual offenders and bring them before the courts to be punished for their appalling crimes and achieve justice for their victims.'