Hundreds of motorists have had their driving licence revoked after failing roadside eye tests under new police powers, new figures have shown.
Cassie McCord, 16, died in 2011 from serious head injuries when 87-year-old Colin Horsfall lost control of his vehicle in Colchester, Essex. It later emerged he had failed a police eyesight test days earlier but a legal loophole meant he was allowed to continue driving.
Her mother, Jackie Rason, campaigned for a change in the law and this eventually led to the introduction of new powers - popularly known as Cassie's Law - which allowed the Driver and Vehicle Licensing Authority (DVLA) to revoke licences more quickly.
Figures obtained by the Press Association under the Freedom of Information Act show that since the powers were introduced in 2013, police forces across the UK applied 631 times to revoke licences based on failed attempts to read number plates.
In the vast majority of cases - 609 - the DVLA went ahead and revoked the drivers' licences.
Mrs Rason told the Press Association this was "brilliant news" which had potentially saved dozens of lives.
She said: "I had no idea until now that is was being used so widely and it is very satisfying to know it is making a difference.
"That's more than 600 people who could still be driving, perhaps without even knowing there was a problem with their sight.
"You can't say that in every case they would have killed somebody, but it is very likely to have prevented fatal accidents and other casualties."
Three days before Cassie's death, police in Essex had spent two hours trying to persuade Mr Horsfall not to drive again after he was involved in a minor collision and failed an eye test.
At the time, officers had no powers to immediately suspend a licence and he went on to mount a kerb, hitting Cassie as she walked with a friend.
Under the new procedure, where an officer feels the safety of other road users will be put at risk if the driver remains on the road, they can request an urgent revocation of the licence through the DVLA.
There are three levels of revocation under the new system - immediate, within 48 hours and postal, whereby the driver will be dealt with via letter sent within 24 hours of notification from the police.
If a banned driver continues to drive, they commit a criminal offence which may lead to their arrest and vehicle being seized.
Speaking when the change was introduced, Sue Harrison, Essex Police's Assistant Chief Constable, said: ''I very much welcome this new procedure.
"It is a positive step forward and will enable our officers to immediately refer serious cases to the DVLA.
''This new procedure is a great testament to Jackie's relentless determination and resilience, which I highly commend.''
Mrs Rason said she now hopes to continue campaigning for mandatory eye tests for all drivers and extra checks for over-70s.
She added: "If your car is more than three years old, you have to have an MOT to certify it's roadworthy. Why shouldn't that be the same for drivers?"
Individual police forces said could not say how many times they had made applications under the new powers, known as D751E referrals, because such information is only recorded in officers' notebooks.