A former teacher who says her career was ruined when one of her pupils poisoned her drink with blackboard cleaner has launched a £700,000 compensation claim.

52-year-old Shaaira Alexis of Bermondsey, South-East London, drank the fluid after a female pupil sneaked into her classroom at Brampton Manor School in Newham, East London, and poured it into her drinking bottle.

The High Court heard that the girl had been given the key to the classroom by another teacher at the school and that Miss Alexis became ill the following day after drinking from her water bottle.

Miss Alexis’ barrister William McCormick told the court that although her physical reaction to the poisoning was relatively short-term, the psychiatric effect on her was devastating. He added that as a result of what happened to Miss Alexis, her hopes of being promoted to head teacher, or a least a department head or deputy head, were left in tatters because of her psychiatric injuries. Miss Alexis is said to have been so scared of leaving her classroom when she returned to work that she once urinated in a wastepaper bin. She eventually lost her job as a teacher at the school in August 2006 as a result of her poor sickness record.

Mr McCormick said that she felt she was not getting the support she required and she felt that the incident was not treated seriously enough. He said: “The traumatic consequences of the schoolgirl’s prank remain with her to this day”. Miss Alexis is claiming for £700,000 compensation from the London Borough of Newham, to cover the costs of loss of earnings and pension entitlement as well as emotional distress caused by the incident.

The council strongly denies that it was negligent in any way and also disputes the value of her compensation claim. Arun Katyar representing the council said told the court: “It is inherently unlikely that Miss Alexis would have reached the heights of the teaching profession”. The council said it plans to call evidence from her colleagues at the school who say she would have been held back in her career by her “racism and poor grammar”.

Mr Katyar argued that “her days in the teaching profession were likely to be numbered”, even if the poisoning incident never occurred. However Miss Alexis’ solicitor, Mr McCormick said that the allegations made against her form part of a “nasty undercurrent” which has developed since Miss Alexis filed her compensation claim, adding that she had previously been described as an excellent teacher and a valuable member of staff. He told the court that Miss Alexis’ prospects of career progression were very, very good.

He accused the council as being negligent in the fact that a pupil was given access to a classroom posing a risk to teachers and pupils. He added that in recent years there had been a string of extremely nasty attacks on teachers by students at the school, with pupils ganging up on staff.

The school has 1,450- pupils and is in an area affected by social deprivation in East Ham, but in the latest inspection by OFSTED, the school was praised as “a good and improving school with some outstanding prospects”.

Since losing her job, Miss Alexis has given up teaching and has pursued a number of business ventures without financial success.

The case continues.