A teenage girl told a court today how a crush on her maths teacher led to secret sex sessions and the pair running away to France together.

The girl at the centre of a child abduction case told Lewes Crown Court via videolink of her “biggest secret ever” and how she developed a relationship with the teacher Jeremy Forrest when she was 13.

The pair sparked an international manhunt after disappearing together for eight days last September, the court heard.

Forrest, 30, watched intently from the dock as the jury was shown the video of her interview with detectives six days after she was brought back to the UK.

The 15-year-old said: “I had a crush on him, I found him really attractive. I had had boyfriends but he was older and more mature. But nothing happened until a year and a half later.”

She said they had held hands on a long flight back from a school trip to Los Angeles “but in an innocent way”.They started exchanging tweets but the school authorities found out and put a stop to it.

“So we started texting each other and it started with a lot of kisses and conversations started getting a a lot more flirty,” she went on. “Gradually we got into a a loving relationship. There were photos and stuff passing between us and other text messages.”

She said that after the relationship beginning in term time, it became sexual in the school summer holidays.

When they went back to school in September the police moved in and when she had to hand over her phone she “panicked”. That night she packed a bag and rang Forrest the following day. “It was like our biggest secret,” she told jurors.

Forrest picked her up and drove straight to Dover to catch a a ferry to Calais, she said. They drove through the night to Paris and parked outside the Gare du Nord. There she dumped her school top and bag in a a bin but kept the school skirt and cardigan.

Without sleep for 24 hours they arrived by train in Bordeaux and checked into a hotel.

“We tried to lay low but our money started to run out. We tried to get a job and made fake CVs and a French phone,” she said. “We didn’t want to be recognised and I dyed my hair and Jeremy dyed his hair.”

But on the way to a job interview they were intercepted by French police.

Earlier the court had been told that Forrest had been married less than a year when he started sending increasingly flirtatious and intimate messages over twitter to the girl.

Prosecutor Richard Barton told the court: “But this was not Romeo and Juliet. This was a gross and long term breach of trust.”

Forrest denies child abduction.

The trial continues.