A former vet has lost a Court of Appeal bid to reduce the length of his prison sentence after drugging and sexually abusing young boys at a summer camp.

Jon Ruben, 77, who was labelled by his wife as a ‘sadistic, monstrous paedophile’, used the ‘cloak of Christianity’ to carry out his sex attacks on vulnerable children, Leicester Crown Court previously heard.

The summer camp leader was jailed for 23 years and 10 months at a hearing in February, with Ruben told he would serve a further period on licence, bringing his total sentence to 31 years and 10 months.

He had pleaded guilty to sexual assault of a child under 13, assault of a child under 13 by penetration, eight counts of child cruelty, three counts of making indecent images of children and four drugs charges.

The families of the victims also attended the hearing remotely. At the end of the hearing, three judges said they would change the structure of Ruben’s sentence, but declined to reduce the length of the jail term or extended licence period.

Ruben laced sweets with tranquilising drugs and attacked two children last year after playing ‘a sweet game’ with the youngsters at a summer camp at Stathern Lodge, in Stathern, Leicestershire.

Thomas Schofield KC said: ‘This was a very serious set of offending, and it required a serious sentence.’

He said there had been ‘double counting’ with the drugging of two of the boys when calculating the sentence, and that some counts should not have been given consecutive sentences.

Mr Schofield also said that ‘the demonstrable remorse of the appellant’ had not been properly considered and reflected by the sentencing judge.

The Crown Prosecution Service opposed Ruben’s bid to reduce the length of his prison sentence.

Mary Prior KC said: ‘This was a little boy who had to comprehend what had occurred to him whilst he was asleep. His humiliation, embarrassment, and shame he felt were clear from his mother’s victim personal statement.’

Ms Prior said there was ‘very significant planning’ by Ruben when he injected the sweets with drugs.

She said Ruben had used his veterinary skills to determine the appropriate dose of sedation and chose the smallest children.

The barrister later said there was ‘later remorse’ from Ruben, who had originally pretended not to know what drug had been used when eight children were admitted to hospital, and that he had not said what one child was penetrated with.

Mr Justice Swift, sitting with Lord Justice Jeremy Baker and Mr Justice Kimblin, said Ruben’s offending was ‘extreme’, and added: ‘The appellant’s offending was by any measure extremely serious and entirely shocking.’

‘The judge did make allowance for the appellant’s age… We see no reason to second guess the allowance made.’

The length of Ruben’s prison sentence and extended licence period did not change.