Driving instructor Stephen Cooney, 51, groped three female learner drivers in a series of attacks on Teesside dating back to 2002.

A jury at Teesside Crown Court found him guilty of two indecent assaults and two sexual assaults.

Cooney, of Marske-by-the-Sea near Redcar, told the court the carrot incident was a "practical joke".

The court heard how Cooney put the 12-inch carrot down his trousers and told a pupil in her 40s that a perfectly executed manoeuvre was so good that it had given him an erection.

He then took her hand and made her touch the vegetable before showing her the carrot, the court heard.

He denied placing her hand on his groin, but admitted hiding the vegetable in his pocket.

Naked photos

He told the jury: "I admit it was unprofessional, stupid, and I regret doing it.

"I just thought maybe I would play a practical joke, but obviously it was stupid."

Jailing him, Judge George Moorhouse, said: "You were in a position of trust."

Giving evidence, another of Cooney's pupils said when she failed her test he offered to waive the £80 she owed him if she pulled over into a lay-by and had sex with him.

She told the court: "I just said 'No thank you, Steve'."

He regularly groped her during lessons between August 2005 and February last year, the court heard.

When police arrested him they also found naked photos in the glove box of his Vauxhall Corsa.