A former  Scout leader and council finance official has  admitted sexually abusing young boys after a number of videos and films he had taken of the activities were found in a police raid.

Henry Calder, 60, who had been in a position of responsibility in the Scout Association for about 40 years, had taken videos between 1982 and 1991 at camps organised by the movement.

He had also been an employee in the finance department at East Dunbartonshire Council until his retirement in 2010.

Calder, of Kirkintilloch, was arrested in a raid organised under the auspices of Operation Alba, which targeted people who downloaded child pornography on the internet.

Officers who went to his house found tapes which depicted naked young boys committing various sexual acts and in which his voice could be heard urging them to commit indecent acts. Yesterday, Calder admitted at the High Court in Glasgow to five charges of lewd and libidinous practices and behaviour at Auchengillan Outdoor Centre in Blanefield, Glasgow, and Fordell Firs National Scout Activity Centre, near Dunfermline in Fife.

Calder also pled guilty to downloading images of young children between December 16, 2004 and July 5, 2012.

Prosecuting, Alison di Rollo told the court: “In July 2012, police received intelligence as part of Operation Alba – an operation targeting online sexual abuse of children – which suggested a particular IP [internet protocol] address allocated to the accused was responsible for downloading indecent images of children.”

A search warrant was obtained for Calder’s home, where a substantial number of indecent images were found. Police also seized a sizeable quantity of VHS and Betamax video tapes, 8mm tapes and discs.

Ms di Rollo added: “An incident room was set up in Kirkintilloch police station and equipment found to play the tapes.

“It was found in general to be footage taken by the accused mostly at Scout camps in the 1980s and 1990s. The accused’s voice is heard and he is seen throughout interacting with the boys.

“Officers found a significant quantity of footage of Scouts variously in a state of undress or naked in a large Belfast sink and pouring chocolate over each other. These were referred to as  “chocolate baths”.

On one of the VHS videos, Calder, a first offender, is seen to write a slogan on the stomach of a boy with an arrow pointing to his private parts. At another point Calder is heard to say: “This is rather pervy.”

In one film he commented on a boy’s bottom, and in another video he urged a boy to dance naked.

Judge Lord Turnbull said: “I can’t help but wonder where the other adults were when this conduct was being engaged in.”

Defence counsel Dale Hughes told the court: “This activity was not as clandestine as one might expect. There were boys and adults coming and going and the video camera was set up on a tripod.”

Mr Hughes said Calder suffers from hypertension and asthma.

The court heard that he had 140,201 indecent images of children and 4870 moving indecent images of children.

Lord Turnbull placed Calder on the sex offenders register and deferred sentence on him until next month at the High Court in Livingston.