The details emerged in journalist Louis Theroux's latest documentary on the deceased entertainer, called Savile, where he spoke to a woman named Sam (below).
Sam said she met Jimmy Savile while she was staying in Stoke Mandeville hospital in Buckinghamshire.
She was 11 years old when the former DJ, presenter and fundraiser (main picture) abused her, revealing that she used to wear extra layers of clothing to protect herself.
The abuse would always take place while the services were going on.
Sam speaking to Louis Theroux
Speaking to Louis Theroux, she said: "Our paths used to cross because we used to go to church on a Saturday evening, which is where he used to go, because that was on the hospital premises.
"My job at church was to take the collection plate around. There was a little presbytery room, and that's where I used to go and get my collection plate.
"And he used to go and stand in there, so I'd go in, I'd get the plate - which would always be behind Jimmy Savile - so I always had to reach to get the plate, and then he would do whatever he wanted to do.
"He would never sit with the congregation. He would always be in the back room."
After his death in 2011, it emerged Mr Savile was a widespread abuser of women and children. At least 450 people have made complaints against the late DJ, with the youngest being the age of 5.
Sam went on: "It was easy for Jimmy Savile. What he was doing was no difference to what had been happening all my life. He picked really easily and well.
"I just used to think hurry up that bit of the service so I could come out, but then I knew I had to go back in the room."
