The trial heard how the abuse came to an abrupt halt in 1970 after Mr Blanchard’s mother and sister finally became aware of what was happening.
By that time, Mr Blanchard’s family had moved away to Pudsey and he was no longer a regular visitor to St Stephen’s.
But Endersby was still determined to continue the abuse and would regularly ring his victim’s home to try to get hold of him.
He would persist in making the calls several times a day, pretending to by a schoolfriend of the youngster when the phone was answered by one of his relatives.
Mr Blanchard’s sister became suspicious and then challenged Endersby when she worked out that he was making the calls.
His sister and mother then managed to get Mr Blanchard to tell the truth about what had been happening.
His mother contacted Reverend Ward but he refused to investigate the matter and accused Mr Blanchard of lying.
Prosecutor Richard Gioserano told the jury: “The vicar accused the 15-year-old Roy of being a filthy liar, whereas the defendant was an upstanding member of the community.
“When Roy’s mum hinted that she might take things further, the vicar said that there were plenty of God-fearing church folk around and things could get very difficult for the family.
“Roy understood why his mother let it go - she did not want the scandal and it was all too much for her to deal with.”
Endersby was able to continue with his life unscathed by controversy.
Endersby was a magistrate in Leeds until 1995 when he stepped down from his position after he committed a sexual offence which this time he was unable to cover up.
He was arrested after he sexually assault an undercover policeman in a public toilet in Bradford.
The father-of-two admitted the offence and received a conditional discharge by magistrates but managed to continue as a senior member at St Stephen’s church.
Reverend Ward remained at St Stephen’s church until 1976. He was then the vicar of Bramhope for more than 20 years before retiring in 2005. He has since died.
A spokesman for the Diocese of Leeds said: “Kenneth Endersby, who is 84, had been the choirmaster at St Stephen’s Kirkstall since 1966. He was suspended from this role in October 2013 when the allegations first came to light.
“While these events happened over 40 years ago we know the impact on survivors is life-long, and we are profoundly sorry for the harm Kenneth Endersby caused to this young member of the congregation who trusted him.
“We were also very sorry to hear in court that his trauma was compounded by the response of the vicar at the time (who is now deceased).
“The Church of England has implemented stringent safeguarding procedures (including the training of clergy and lay people), which it continues to assess, and it always takes very seriously any allegations of inappropriate behaviour and abuse, which are immediately reported to the police.
“We also work with other agencies to ensure that our churches are places of safety for all. And we continue to hold everyone involved in this case in our prayers.”
Acting Detective Inspector Matt Knowles, of the Leeds District Child Safeguarding Unit, said: “Endersby abused his position of trust to sexually exploit a vulnerable young boy over a significant period of time.
“The long-term trauma that such offences cause to victims should never be underestimated, and we hope the victim in this case can take some comfort from knowing that his abuser has finally had to face the consequences of his actions.
“West Yorkshire Police treats any allegations of this nature seriously and has specialist safeguarding officers who will investigate and ensure victims are fully supported throughout the process.
“This case again illustrates that the passage of time is no barrier to justice.”