Dr Davidson had graduated from Oxford and was engaged

Elizabeth Davidson, from Hamilton, lost her daughter Margaret, 26, in a car crash in May. Her 19-year-old killer was sentenced to four years in jail.

Ms Davidson said courts must impose the maximum sentence available of 14 years.

Her call was made as she backed plans by insurers to make learner drivers take lessons for at least 12 months.

The Association of British Insurers has urged the government to adopt its proposals to improve road safety.

The plans are backed by motoring and safety groups such as the RAC Foundation, which said they would lead to 1,000 fewer road casualties a year.

Mrs Davidson said: "It might bring home to other young people and other drivers the dangerous weapon they are handed when they get that little slip that says you are now a driver."

Reduced to tears

Dr Margaret Davidson was driving home to Kidlington, Oxfordshire, when she was killed by Nolan Haworth.

I loved Margaret from her first breath and will love, mourn and miss her until my last Elizabeth Davidson

His Vauxhall Nova crashed into her at more than 70mph after overtaking on the brow of a hill.

Under the new proposals, he would have been made to take driving lessons for a year before being qualified.

But Mrs Davidson said: "I'm not sure there is any legislation that would stop this particular young man doing what he did

"He appears to have been a young man with no respect for authority or the law."

She urged the courts to make use of the maximum sentences available.

"I don't think anyone has ever served 14 years and I wonder why," she said.

"What is the point of having an upper level if it is not brought home to someone by giving them 14 years."

During Haworth's sentencing Judge Julian Hall was reduced to tears when Ms Davidson read a victim impact statement.

In the statement, she described her daughter as beautiful, fiercely intelligent, caring and thoughtful.

"My heart is broken," she said.

"While I am devastated she has been taken I would rather suffer this pain than never to have the love we shared in those 26 years.