Lauren Cox, 27, from Surrey, had an affair with a 16-year-old schoolboy

Two mothers clashed at court yesterday after a teacher was jailed for 12 months following an affair with a 16-year-old pupil.

The mother of the teenage boy had been praised by the judge after turning detective to expose the relationship between her son and geography teacher Lauren Cox, 27.

And in an extraordinary exchange, as she left Croydon Crown Court the boy’s mother told Cox’s tearful mother: ‘I didn’t have a choice, he is my son.’

Cox’s mother replied: ‘You did have a choice. How do you sleep at night?’

The married teacher, who last month admitted five counts of sex with a child in her charge, had screamed and said ‘I’m sorry’ to her family as she was led to the cells.

Cox – known as Miss Dunlop until her marriage during the grooming campaign – met the boy when he was 13.

She would give him sweets but initiated a sexual affair after he turned 16.

Brian Reece, prosecuting, said in February last year she gave the boy a lift. ‘She stopped the car and gave him three choices,’ said the prosecutor. ‘They could either sit in silence, she could simply drop him at the station – or they could hug.

‘He chose the third. This was the first step into what she knew was forbidden territory.’

The relationship became more physical and full sex began in March, first in her car in a field.

She even went on the pill, telling him it would ‘feel better’ as they had sex on ‘multiple occasions’, including at both their homes.

Cox also sent him indecent selfie videos and ‘questioned him like a jealous girlfriend’, said Mr Reece. ‘She told him to keep the relationship secret. He tried his best to act normally in school.’

The affair began to unravel when the boy’s little sister came home early one day.

Cox, who pleaded guilty to five counts of sexual activity with a boy aged 13 to 17, will return to court next month to learn her fate

The pair thought they had managed to slip out unseen but the sister had seen women’s sandals in the porch and a strange car outside.

The boy had already invented a girlfriend called ‘Hannah’, 16, to explain a change in his behaviour to his parents.

After the car was spotted he made up ‘Grace’, 18.

But his mother was unconvinced and her suspicions intensified after her son abandoned plans to study medicine and said he would instead take geography at Sussex University and then be a teacher. Cox had done the same.

The mother dramatically proved her case when she spied on her son and saw him picked up by Cox in the car seen at the family home.

Cox screamed as she was jailed today, after she pleaded guilty to five counts of sexual activity with a boy aged 13 to 17 at Croydon Crown Court

At this time the boy was on study leave for GCSEs and the teacher, who was head of geography at the school in south London, had taken time off to have sex with him.

Last August, the mother summoned Cox to a coffee shop showdown where the teacher tried claiming she was giving ‘extra tuition’ before confessing her relationship and agreeing to end the affair and resign.

But Cox requested a final goodbye – at which she had sex with the boy again – and in her resignation letter she did not admit the affair.

At that point it is thought social services were informed and police became involved.

The boy said in a victim statement: ‘Lauren emphasised the need for secrecy, which led to me distancing myself from family and friends. She would request to see me during the run up to my GCSEs. I felt trapped. Since it all came out some teachers blatantly ignore me, some show disgust.’

Cox, of Oxted, Surrey, is being divorced by husband Andrew, 30.

Her barrister Ronnie Manek described her as ‘emotionally vulnerable’.

Cox was dumped by her husband and kicked out of her home after she was found out and she has since moved back in with her parents

In a letter to the judge, she said: ‘I’d like to apologise to [the boy] for putting my heart in front of my head. I fell in love and thought the feeling mutual. If there’s any small chance I might resurrect my career, I will fight for it.’

But she is set to be barred from teaching and wept in the dock as Judge Adam Huddleston told her: ‘You have not just been a shame and disgrace to yourself, you have brought teaching into disrepute.’

He commended the boy’s mother for her ‘calm and sensible reaction’ to the situation, which he said must have been a considerable shock.

The judge told Cox: ‘After you made a full confession you begged to break the news and she allowed you do to so.

‘And then you didn’t do as you said. At that further meeting you had sex with him again in a flagrant breach of the trust instilled in you by his mother.

'Despite being warned to desist by the victim’s mother you offended again.

Cox, seen being driven away from the court, had a sexual relationship with the 16-year-old boy she was teaching between March and September last year

The events fuelled a rumour mill at the school, which cannot be named for legal reasons. Parents said Cox was well known for her 'forward' manner with boy pupils.

One said: 'I remember her from a parents' evening. The way she greeted one of the boys, it certainly raised an eyebrow.'

Another claimed a mystery whistleblower had plastered buildings with Post-it notes in a bid to raise the alarm about the improper relationship.