Kate Kirman, who worked as a receptionist and first aider at the King's Hill School, received gifts at a special presentation recently.
Headteacher Jane Rutherford said the school wished Kate, who is retiring to Lincoln to be nearer her son and family, the very best.
"Over the 22 years that Kate has worked at King Edward VI School she has supported countless students, staff, parents and visitors," said Jane.
"There is no shortcut to building long-term rapport with people and Kate has always had the best interests of the school at heart.
"In school you have to be prepared for anything, dealing with a medical emergency, answering random questions from students, liaising with parents and supporting staff
"Just getting the right person to the right place in a school with over 1500 students is no easy task."
Jane said Kate's role had extended to diplomat, counsellor, juggler, event planner, postal service "and so much more".
"A school is only as good as the people in it and Kate is one of the best," Jane added.
"She will be a hard act to follow and very much missed by us all.
"We wish her well in her new ventures."