"Mrs Kent", as she is known by staff and children, taught music incognito at Wansbeck Primary School, coming to Hull once a week from her home near Oxford for 12 years, before "retiring" at Christmas.
But yesterday she revealed that as well as remaining as school governor, she would continue to teach there on a supply basis, as well as pouring her efforts into her new charity Future Talent.
The charity grew from her realisation that there were many musically-gifted children at the school – and schools everywhere – who needed help if their talent was to blossom.
Since its launch last November, the charity has provided a specialist music teacher, Elizabeth Emanuel, to Wansbeck Primary and its sister primary school Longhill, where five "exceptionally talented" children have already been identified.
An accomplished musician and freelance player for several major London orchestras, Mrs Emanuel now works at each school two days a week.
The Duchess told the Yorkshire Post: "All children can achieve in music and some can excel. They stand better, their posture is better – you can even do maths to music!
"In very basic terms it can help. When I was a teacher and a child said her nan was in hospital and she had been crying I said we would sing a lovely song for her. We would do something like Danny Boy and then they have got it out of their system.
"They also concentrate particularly when they are performing, they have to communicate and they have to understand the words so their English is improved." The school now has a cello, three violins, three clarinets and a saxaphone, but with over 230 children needs many more to go round. Headteacher Louise Fraser said: "The will is there, the passion is there. We know it makes a difference to the children."
The children were clearly delighted to see Mrs Kent. Sophie Bowser, eight, who has a sweet singing voice, said: "I didn't know she was coming till today. I like her because she is nice and sings songs with us. I like singing and I always try my best."
It was only revealed last year that the enthusiastic and fun-loving music teacher who had been coming to the school every week was in fact one of the best-known Royals.
The remarkable story began when the Duchess visited the school in an official capacity.
She agreed to an unofficial return visit a few months later, and asked staff what they felt the school and the area was lacking.
When they said they needed help with music lessons, she offered her own services.
Through her Royal connections, she has arranged for the children to sing with the Halle Orchestra, and perform with opera star Lesley Garrett at Westminster Abbey.