But, when officers initially arrested him, Derrett, who was an organist at Holy Trinity for two years and now lives in Keyingham, confessed that he was also guilty of historic sex offences alongside creating the thousands of perverted images.
During his police interview, he told officers that he had sexually abused three boys dating to the period November 1977 to November 1980 while working in the Shropshire area.
Mr Robert Edwards, prosecuting barrister, told the the hearing at Shrewsbury Crown Court on Tuesday: “In December 2016 the defendant was arrested by police in Humberside as attention had been drawn to him over concerns that he was in possession off indecent images of children.
“He was subsequently prosecuted and jailed for 12 months.
“During the course of that interview he volunteered that he was responsible for historic offences. He disclosed that he had been a church choir leader and the offences were while he had been working in schools in the Shropshire area.
“He gave details of three children, all would now be adults. Only one of them them was traced and it is only he who has made a statement of complaint.”
Mr Edwards told that the victim recalled that he was aged 13 to 15 when he was assaulted on a number of occasions at Derrett’s home address when they were alone.
Derrett, of Ings Lane, Keyingham, was a choirmaster and music teacher, and first met the victim at choir rehearsals and later offered him music lessons. The victim described how the offences were “occasional and sporadic”.
n his previous sentencing at Hull Crown Court , the court heard that in one of his interviews, he had “talked about finding boys aged 14 and upwards sexually attractive, but to get aroused I need them younger”.
Sentencing Derrett to 20 months immediate imprisonment, Mr Recorder Stephen Thomas told him if that he had subsequently denied the charge and then been found guilty by a jury after a trial he would have been jailed for 30 months.
Derrett is subject to a Sexual Harm Prevention Order for six years and a notification order. He must serve at least half the jail term before being released on licence.
Ex-Holy Trinity organist jailed for making thousands of sick images of children
A musician, teacher, and former organist at Hull’s Holy Trinity Church has been jailed for a year for making thousands of “perverted” images of children.
John Derrett’s collection was so vast police were only able to view and categorise more than 11,000 images – leaving nearly a million untouched.
Derrett, who had “glowing” references – including from a director at an Oxbridge college – made such frank admissions to Humberside Police, another force is now investigating further potential offences.
But despite those ongoing inquiries, Derrett, 64, was sentenced for the images at Hull Crown Court on Monday after pleading with a judge to conclude his case.
He told Judge Mark Bury: “I feel very ashamed and very aware these are my fault. I will accept what comes and I appreciate the consideration I’m being given.”
None of the images seen by police were photographs or videos of actual child abuse, the court heard. The father-of-two and grandfather made the images by superimposing children’s faces onto pictures of adult pornography.
“They are his own perverted creations,” said Derrett’s barrister, Dale Brook.
He also added his own captions, which were too explicit to publish, but one example read by prosecutor Cathrine Kioko-Gilligan was about a boy needing hospital treatment after being sexually abused.
The images all featured boys aged between nine and 14. Derrett also had legal “naturist” images, mostly of children.
Of the images viewed by police following their visit to his home on December 12 last year, there were 1,675 images and 114 videos at Category A – the most serious; 1,314 images and 50 videos at Category B; and 8,233 images and 50 videos at Category C.
He also had “prohibited” images of children, although it was not explained how these differed from the indecent images, and extreme pornographic images featuring animals.
A further 983,673 images found in his possession were not examined.
Derrett, of Ings Lane, Keyingham, admitted three counts of possessing indecent images of children, possessing prohibited images of children, and possessing extreme pornography.
The judge noted that in one of his interviews, he had “talked about finding boys aged 14 and upwards sexually attractive, but to get aroused I need them younger”.
Derrett had been a school teacher and music teacher until his retirement in 2000, worked with choirs until 2007, and was organist at Holy Trinity between 2005 and 2007. The offences spanned 2008 to 2016.
One of Derrett’s references was from the director of music at Keble College, Oxford.
“He’s got some heavy duty references, hasn’t he, Mr Brook,” said the judge after reading them.
Jailing Derrett, the judge told him: “I’m afraid in all the circumstances you can’t be dealt with in any other way than an immediate sentence of imprisonment.”
Derrett was made subject to a sexual harm prevention order for seven years, and must register as a sex offender for the same period.
An investigations into possible further offences by Derrett is being conducted by West Mercia Police.