Alexander Charles Ralls, 47, who was deputy head of boarding and deputy child protection officer at Queen Ethelburga’s School in Thorpe Underwood, North Yorkshire, has been convicted of more than 40 sexual offences against pupils, the Harrogate Advertiser has reported.

Queen Ethelburga’s Collegiate incorporates four boarding and day schools for girls and boys from three months to 19 years old.

Ralls was accused of sexually abusing 20 girls over a three-year period and charged with 48 separate offences including 37 sexual assaults and 10 counts of causing a child to engage in sexual activity. A jury found him guilty of all but four of the offences following a four-week trial at Bradford Crown Court.

Ralls also worked on behalf of an international charity bringing relief aid to impoverished people in India and The Gambia.

Students at Queen Ethelburga’s and other schools were given the opportunity of travelling to The Gambia and India on trips organised by Ralls. 18 of the 20 girls who made complaints about Ralls were Queen Ethelburga’s pupils who had been on his trips to India and the West African country.

He encouraged girls to take showers in front of him and performed intimate ‘health checks’ after many of them fell ill because of the excessive heat.

Prosecutor Peter Hampton said: “The defendant had a sexual interest in pre-pubescent and adolescent children and teenagers. He had the opportunity to pursue that interest and commit the offences because of who he was and the job he held.

“Alexander Charles Ralls was a fraud – he would deceive the girls into believing that his touching of them, or other activity, was a necessary and legitimate medical procedure, when in fact, it was not. His actions were driven by his own sexual motivation and interest. He is a fraud not only in the manner in which he committed the offences; he is a fraud in the way in which he presented himself to the outside world.”

Ralls was dismissed from Queen Ethelburga’s in December 2015. He will be sentenced on Friday 28 July.