Angry Caroline McDevitt has enlisted police to try to trace the driver, who drove a white estate car with the logo Skyline on the side.
But so far they have drawn a blank – and Skyline say they have no knowledge of the driver.

The drama started when schoolgirl Melissa McDevitt discovered her bicycle, which she uses to travel from St Paul's school to her West Bletchley home, had been vandalised in the bike sheds and could not be ridden.

"The school staff were very good and booked a taxi to take Melissa home. They said they would pay for it on their own account," said Caroline, who was out at a hospital appointment at the time.

"Melissa waited outside and a cab drew up. She asked if it was for her and when the driver said yes she got in."

But at the end of the journey the driver asked the schoolgirl for payment – and threatened to keep her pink school rucksack if she did not produce the cash.

"Melissa rang me in a real state. I told her to stay calm and tell the driver to return later, when I would pay the fare," said Caroline.

But before Melissa could relay the message the driver had disappeared – complete with the bag. Checks later revealed the cab was NOT the vehicle booked by the school.

"It's been over two weeks now and no-one can find this mystery driver and there is no trace of my daughter's bag. She's lost her books, her pencil case, her homework and she's had to do all her schoolwork again," said Caroline.

"I find it really worrying that there's a man around that can pick up children this way ...I just thank my lucky stars that Melissa was unharmed."

Anyone who knows anything about the mystery white cab, driven by a slightly balding Asian man in his early thrities, should contact police on 0845 8505 505.