A former community centre caretaker jailed for more than 15 years for a catalogue of rape and abuse against vulnerable children and adults has lost an appeal against his sentence.

David Robertson, 58, challenged the penalty imposed on him by a judge who branded him "a substantial risk to the public" while at liberty.

His lawyers brought forward an appeal after the sentence was handed down at the High Court in Edinburgh in 2014.

Lord Menzies, sitting with Lady Cosgrove, rejected the appeal at the Court of Criminal Appeal in Edinburgh.

Robertson was sentenced to 15 years and four months by Lord Boyd of Duncansby and ordered to be kept under supervision for a further ten-year period.

The judge told Robertson, formerly of Shapinsay Square in Aberdeen: "No one who sat through this trial could fail to be moved by the accounts of abuse at your hands."

Robertson was convicted of 25 offences involving 16 victims, including raping two women and a girl between 1975 and 2011.

The sentencing judge pointed out that seven of victims were underage girls, two were adult women with learning difficulties and one of his two male victims also had learning difficulties.

Robertson, who formerly worked at the Lord Provost Henry E Rae Community Centre in Aberdeen, preyed on victims at a holiday village in Arbroath and at a caravan park.