A humanities teacher has been struck off for incompetence, despite a lack of "robust" evidence to prove that pupils made insufficient progress in her lessons.
Denise McKillop has been banned from the classroom after the General Teaching Council for England found her guilty of a series of failings over a five-year period.
Only 11 other teachers have been struck off for incompetence from a workforce of around 500,000 since the GTC was formed in 2001.
As reported in The TES earlier this year, most local authorities have not referred a single teacher for lack of ability, leading to criticism that substandard staff are being allowed to continue their careers.
It is feared incompetent teachers are being recycled among other schools rather than removed from the profession.
Ms McKillop, who taught at Peers School, now Oxford Academy, was found guilty of weaknesses in her subject knowledge, lesson planning, marking and classroom management between 2002 and 2007.
The GTC said this was a "significant period of time" to fail to reach the standard expected of teachers.
Ms McKillop was given extensive support by the school and external specialists, but failed to improve, a GTC professional competence committee ruled.
A number of evaluations identified concerns with "inadequate" lesson planning, the committee said.
Marking did not adhere to the school's policy and failed to make comments that would help pupils develop understanding, it added.
Ms McKillop's overall standard of classroom management was also found to be "inadequate", despite occasional successes and having a number of pupils with learning difficulties in her lessons.
Despite these weaknesses, the council found that there was insufficient evidence to prove student learning and progress had suffered.
The GTC said it gave "credence" to testimony from the school's acting deputy head that pupils "demonstrated insufficient development and progress" in her classes.
But the evidence was not "robust enough" to prove the allegation. There was a lack of information comparing pupil performance, the committee said.
The GTC raised concerns that Ms McKillop had shown "no understanding or insight into your failings, actions or your lack of competence". It said she had not followed the advice given to her and had not shown herself willing to address her problems.
"The areas in which you have failed to achieve the required standards are fundamental elements of teaching," the ruling said.
"Failing to reach the required and reasonable standards over such a significant period of time does identify a serious falling short of the standard of competence expected of a registered teacher.
"There is a risk that pupils' knowledge, education and attainment could be affected.
"We are equally concerned that your perception of your ability as a teacher is not consistent with the evidence which we have considered in this case."
Ms McKillop is banned from the classroom for two years, after which she can apply to rejoin the teaching register. Applications are subject to further hearings at the GTC and are not automatic.
Ms McKillop is the second teacher to be struck off for incompetence this year. The other was David Lee, a former head of music at Selston Arts and Community College in Nottinghamshire.
Harassment head: 6-month suspension
A headteacher has been suspended from teaching for six months after harassing a local authority adviser with hundreds of emails and visits to his office and home.
Lynn Spode, former head of Creswell Junior School in Derbyshire, told Kevan Lomas that she had become attracted to him in a platonic way.
When he attempted to cut all personal contact, Mrs Spode sent Mr Lomas emails asking for a reason for his rejection. Other emails were abusive, the General Teaching Council heard.
The harassment occurred between December 2005 and July 2007. Mrs Spode had previously admitted her conduct at a magistrates court and was given a 12- month restraining order in March 2008.