Two teachers have been banned from the classroom for life, as the General Teaching Council for England handed down its toughest sanction for the first time since 2007.
Stephen Carr, who taught at a Newcastle school that cannot be named, had an "inappropriate relationship" with a pupil, texting her and going with her on holiday.
Frank Aboagye, who taught most recently at Sir Frank Markham School in Milton Keynes, was found to have an attitude problem and to have persistently lied to his school.
The unrelated cases take the total to just seven teachers struck off for life since the council was set up in 2001. The last one was in September 2007 after a teacher had started a sexual relationship with a pupil.
Mr Carr's "inappropriate relationship" was with an A-level pupil.
In October 2005, after she told her parents she had been exchanging texts with her teacher, he met them and apologised, and said their relationship would cease.
But the following January a message from Mr Carr was found on the pupil's computer and in the February he sent her a Valentine's card.
He apologised again and said he would resign and move away from the area. Mr Carr did resign, but during his notice period he went to New Zealand with the pupil.
In its ruling, the council said: "The committee considers this behaviour to be a most serious breach of the standards of propriety expected of registered teachers.
"Pupil A was doing well at school and she was expected to go to university. The breach of trust that led to this relationship disrupted her school experience and set back her life chances."
The council criticised Mr Carr's lack of insight and unwillingness to accept responsibility for the relationship, saying that he had "engaged in sustained deception". They also judged that there was a risk he might reoffend.
Meanwhile, Mr Aboagye was found to have "displayed persistent dishonesty over a long period".
The council said that he had lied about his reasons for absence at a previous school and had been dishonest when he denied that any of his former schools had raised concerns about his performance.
He also accepted a job at a new school but did not resign from his previous post, meaning he was effectively employed by two schools at once, the council heard. And in May 2006 he called in sick to attend a conference in China as an employee of another company.
Mr Aboagye said he had been treated unfairly and that he was the victim of racial discrimination, but the council found no evidence of that: "In our view, he has displayed attitudinal problems and no insight into the harmful consequences of his behaviour. We find his behaviour to be fundamentally incompatible with being a registered teacher."