The Police Scotland detective who led the investigation into William Rigby’s sexual abuse of children in Helensburgh says Rigby’s behaviour was among the worst his officers have ever seen.

Detective Inspector Steve Martin spoke after 53-year-old Rigby was handed an Order for Lifelong Restriction and told he will serve a minimum of seven years behind bars.

DI Martin said he hoped Rigby’s conviction would encourage others to come forward to report their experiences of abuse, or to bring concerns about anyone who might pose a risk to children to the attention of police.

Rigby was sentenced at the High Court in Glasgow earlier this week, having pleaded guilty in March to to sexually abusing three girls in Helensburgh.

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The offences took place in 2018 and between 2005-2007. The girls were aged four, six and 11-years-old when the offences began.

DI Martin, from Police Scotland’s Public Protection Unit, said: “The abuse displayed by Rigby towards his victims was horrific and some of the worst my officers have seen.

“I want to praise the courage and strength shown by all of the victims. The account of the youngest victim led us to two other victims and the arrest of William Rigby.

“If you or anyone you know has been a victim of abuse or wishes to report abuse you should feel confident in reporting to Police Scotland.

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“We would ask anyone who has concerns or information about any person who may pose a risk to children or who may have abused a child to contact us on 101.”

That call was echoed by the children’s charity NSPCC Scotland, for whom a spokesman said: “Abuse ruins childhoods and Rigby’s appalling actions will blight his victims’ lives into adulthood.

“He was brought to justice thanks to the bravery of one of his young victims in speaking out, and it is vital they all get the support they need to help them come to terms with what happened.

“NSPCC Scotland delivers ‘Speak Out, Stay Safe’ assemblies in schools and works in the community to prevent abuse and neglect. Anyone worried about a child can contact our helpline to report concerns.”

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Any adult who suffered abuse as a child, or anyone concerned about the welfare of a child, can call the NSPCC helpline for free on 0808 800 5000. Children can call Childline at any time on 0800 1111.