Peele Community College in Long Sutton is looking for its fifth headteacher in eight years with the surprise resignation of Elizabeth Smith.
Miss Smith, head for the last two years, leaves at the end of this academic year this summer.
She will move to Switzerland to join her partner and aims to continue her career in secondary education.
Miss Smith’s time at the school has been dogged by controversy, with some parents objecting to a tougher stance on enforcing rules on school uniform.
In spring last year, more than 50 pupils were detained in “isolation” by the school for wearing non-regulation items, including shoes, but Miss Smith said the school was raising standards by enforcing existing rules and intended to issue more than 500 pupils with free, smart new blazers and ties.
Miss Smith’s headship has also seen the school taking the first steps out of the Ofsted doldrums of “requires improvement” and moving towards being a “good” school.
And last year’s GCSE results showed the school was back on the right track, with highlights such as the 75.49 per cent A*-C pass rate in English and 70.29 per cent A*-C pass rate in maths.
Miss Smith announced her resignation in a letter to parents, telling them: “I have thoroughly enjoyed every one of my five years at The Peele and if it wasn’t for my partner’s permanent relocation to Switzerland I would have remained doing the job that I love.”
She said she would have “relished” leading the school into its next phase, expressed her confidence in its governors to appoint an “outstanding successor and paid tribute to them, its staff, parents and pupils.
And she has insisted her focus will be fully on The Peele until she leaves.
She said: “I just want to leave the school in a very healthy position so my successor can build on the work I have done so far to keep the momentum going.”
The head accepted there had been “quite a lot of negativity” towards her because of the changes made at the school but says that came from a “very small minority” of parents while the majority had been very supportive.
In its most monitoring report from last summer, Ofsted inspectors said effective action was being taken to address the school’s weaknesses.
The area’s county councillor, Chris Brewis, said: “All I can say is the school wants to make sure that whoever is in charge is someone of real calibre and ability and a really forward thinking person to continue the improvements that have happened in recent years.
“I just want to see it succeed because it is such a key part of our community.”