Raymond Connor committed the offences against the girls over a number of years.
The court heard how Connor had touched the genitals of one victim and the breasts of another.
Judge Alison Beards QC said that Connor had also committed offences that, under modern legislation, would be described as “assault by penetration”.
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During a victim impact statement read out to the court, one of his victims said she did not feel like “a complete human” and was still mentally an 11-year-old girl.
She said: “I want people to know how evil (Connor) is”.
Another young girl who suffered at Connor’s hands described feeling “dirty and disgusting” while he “carried on as if nothing had happened”.
She said: “This man was the most perfect man to the rest of the world – little did they know what he was really like.”
Stephen Kemp, mitigating, said Connor, who had served in the military for 25 years, now suffered with “progressive cognitive impairment, likely to be dementia”.
He said the Belper pensioner, also suffering with advanced prostate cancer, had not offended for 14 years and there was “no realistic threat” of repeat offending.
Mr Kemp added: “A custodial sentence of any length is likely to be particularly difficult for Mr Connor – his condition is likely to accelerate his mental and physical ill health.
"In view of his age and health his remaining life expectancy is likely to be short – in custody he will give up all hope, which will significantly shorten his life expectancy.”
Connor, of Ecclesbourne Close, Duffield, Belper was found guilty of 12 sexual offences after a trial.
He appeared at Derby Crown Court via video link from HMP Nottingham, and was sentenced to eight years imprisonment – a reduced sentence due to his ill health.
Connor was found guilty of gross indecency and indecent assault with a girl under 14 years of age, indecent assault on a girl under the age of 16 years, indecent assault on a woman over the age of 16 years of age, assault on a child aged 13 and over by penetration with part of body/ a thing and sexual assault on a woman.
Derbyshire police declined to provide a custody photo of Connor at the request of the victim.
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