A teacher who sent a colleague sexually explicit letters, love poems, red roses and a solitaire ring has been banned from the profession for four years.

Trell O’Hara harassed her former manager after being dismissed for gross misconduct. A General Teaching Council for England (GTC) disciplinary panel said her “deep-seated attitudinal problem” meant it had no choice but to ban her.

Miss O’Hara was sacked from College High School in Erdington, now North Birmingham Academy, in March 2007 for gross misconduct after she swore at pupils and threatened to stab a child. The GTC reprimanded her in October 2008.

But between February and July 2009 she harassed her line manager Karen Smith, who had not been involved in her disciplinary proceedings. She was convicted of harassment by magistrates in Sutton Coldfield in October 2009.

Miss O’Hara made several phone calls to the school between February and March 2009, leaving messages under a false name in an attempt to get Mrs Smith, who was head of English, to contact her.

In February she sent Mrs Smith a greetings card containing a sexually explicit message. Then in March she sent her a dozen red roses and a card containing romantic poetry. She also sent the teacher a solitaire ring.

The two women had never socialised or seen each other outside of school. Mrs Smith had gone on maternity leave in July 2006 and by the time she returned to work in February 2007, Miss O’Hara had been suspended.

Mrs Smith returned her first message, left under a false name, in February. Miss O’Hara told her she wanted to “discuss everything that had happened” but Mrs Smith ended the conversation and did not return any more of the calls.

In the same month, Mrs Smith received a card containing language she thought was sexually explicit. The GTC panel found that the language in this instance was “sexual in nature” but “not particularly explicit”.

The card and roses arrived in March at the school’s main reception. Mrs Smith told the GTC hearing she was “deeply embarrassed and upset” by this.

She contacted the police and two weeks later the school’s own police officer telephoned Miss O’Hara in Mrs Smith’s presence and told her to stop contacting the teacher “or there would be criminal proceedings”.

But Mrs Smith then received a card from Miss O’Hara containing a solitaire ring. Its message contained explicit sexual references which “deeply upset” Mrs Smith.

“It was behaviour directed towards a former colleague which had a detrimental effect on that colleague. Some of the behaviour became known to others and not only had the potential but must have brought the profession into disrepute,” said panel chair Andy Connell.

“In all the circumstances, we have concluded that Miss O’Hara‘s behaviour is incompatible with being a registered teacher and that a suspension order would be insufficient.

“The only proportionate sanction to maintain public confidence in the profession is a prohibition order.”