Teachers’ leaders have written to an education under-secretary following an “obscene gesture” she made to the public outside Downing Street last week.

Education minister Andrea Jenkyns made the gesture last Thursday and later said she had been provoked by a “baying mob”.

The letter, sent on Monday by the NEU teaching union and the NAHT and ASCL school leaders’ unions, as well as Jon Richards, assistant general secretary of Unison, expressed “grave concern at the footage of you making an obscene gesture to crowds outside Downing Street last week”.

“As representatives of the teachers, leaders and support staff who run our nation’s schools and colleges, we are deeply aware of just how important professional conduct, ethical standards and appropriate behaviour are for our children and young people,” it said.

The leaders said that they had read Ms Jenkyns’ explanation that she was responding to a “mob”, “plus your justification that ‘I should have shown more composure but am only human'”.

They said: “Frankly, explanations such as this from politicians are no longer good enough. As role models, politicians are increasingly falling short of the standards expected of them. Your words would certainly not be an acceptable excuse from a pupil or member of staff in a school or college.”

They said Ms Jenkyns should publicly acknowledge the impact that her “loss of composure” will have on education teams’ capacity to “maintain common decency in schools”.

“Given legitimate current concerns about the conduct of those in public life, we are making this letter public,” they said.

Ms Jenkyns had said that a “baying mob outside the gates were insulting MPs on their way in as is sadly too common” as she went to watch prime minister Boris Johnson’s resignation speech on Thursday.

She said she had received “huge amounts of abuse” from some individuals in the crowd over the years and had had seven death threats in the last four years.

She said she had received two of the threats within recent weeks, which were under investigation by police, and that she had “reached the end of my tether”.

“I responded and stood up for myself,” she said, adding: “I should have shown more composure but am only human.”