The headteacher of one of Oxford’s top secondary schools is to step down after only a year.

Neal McGowan, who took charge of Cherwell School, in Marston Ferry Road, last August, said he had agonised over the decision before accepting the headship at a new school due to open in Wandsworth in September 2011.

The Cherwell School, which specialises in science and maths, is the only Oxford secondary rated outstanding by Ofsted.

Mr McGowan applied for his new job at the end of February and accepted the position at St John Bosco on Wednesday, March 31, before telling staff and governors.

He said: “It has been a very difficult decision for me personally and professionally. I reflected and reflected before making the choice.”

St John Bosco, a Roman Catholic school, will replace two other schools in the London borough.

Mr McGowan stressed it was the “almost unique” opportunity to set up a school from scratch which influenced his decision rather than his own Roman Catholic faith or any disappointment at his experience in Oxford.

He initially thought he would spend at least five years at Cherwell School.

Mr McGowan said: “The students at Cherwell are simply outstanding, they’re an absolute delight to work with and that has been the single most difficult issue to face.

“I had become very much emotionally invested in the school and I’m finding the prospect of leaving the students very, very difficult.”

The 46-year-old moved to Oxford from Larbert High School, near Stirling, in Scotland, and will move again to London.

He said: “I’m fully aware of the level of disappointment it will have brought to parents, students and staff.

“Cherwell School is an outstanding school with an excellent reputation and I don’t believe my departure will tear the heart out of the school.”

He promised to work closely with the local authority and the governing body to hand over to his replacement.

He said: “I have no doubt they will find a strong new leader.”

Chairman of governors Kirsten Robinson said she was “surprised and disappointed” at Mr McGowan’s move, but was confident pupils would not be affected.

She said: “Neal is a good headteacher and it has been good fun working with him.

“We will go through the process of recruiting a new headteacher, setting up a selection panel and bringing in professional advice.

“In terms of the school we will set up management arrangements to make sure we continue to thrive and suceed.

“We have a well-established leadership structure within the school, the headteacher is not the sole leader.”

Sally Ross-Smith, from Headington, has two children at the school, Tom in Year 12 and Elinor in Year Eight.

She said: “I was very surprised and a little bit angry that somebody who had taken up what is a prestigious headship should have stayed for such a short time and moved on as quickly as possible.

“He has not made much of an impression on us but I believe him leaving will be disruptive, and it means the school has got to go through another lengthy appointments process.”

The governors have not yet had a chance to discuss a replacement.