A stepfather who moved to Suffolk has been jailed for raping a girl who was returned to his care after social services dismissed her as “troublesome”.

The man and his former partner, the girl’s mother, abused her for up to two months in 1978, when she was around 13.

A jury at Southwark Crown Court convicted the man of two counts of rape and the woman of one of aiding and abetting rape last week. On Thursday, both were sentenced at the same court.

The stepfather was also found guilty of two counts of indecent assault on the girl’s younger sister, referred to in court as C.

The mother was convicted on the basis she “encouraged” the attack on the older girl, referred to as R. None of the parties can be named for legal reasons.

The court heard the victim remembered her mother climbing into bed with her and removing her clothes before her stepfather raped her. The man, who has since split from the mother and was living in the Stowmarket area, has been jailed for 13 years.

Meanwhile the woman, who was arrested in Ireland, was sentenced to eight years in prison.

The abuse happened in West Sussex – years before the man, who is in his 70s, moved to Suffolk. Judge David Tomlinson said: “The betrayal of trust and abandonment of all semblance of care was abhorrent.”

He said the older victim had been “badly damaged” before the attacks, which caused “severe” physical and psychological harm.

In victim statements read to the court by prosecutor Jose Olivares-Chandler, R said: “My childhood is no different from anyone else’s in as much as it has been the foundation of my whole life.

“Where it differs is a world away from happy and normal – instead of being loved, cared for and nurtured I was abused physically and sexually.

C wrote: “I still feel ashamed that my family could do this to me. I will never forget what occurred and will always have it with me.”

The court heard social services interviewed the man in 1979, when he told them the older stepdaughter’s had “come on to” him. She later retracted the allegation, the court heard.

Both defendants were sentenced to eight years for one count of rape, while the man was sentenced to 10 years for the second count, to run concurrently. For indecent assault, he was given concurrent prison terms of two and three years, to run consecutive to the longest rape sentence.