A vigil will be held 20 years after schoolgirl Phillipa ‘Philly’ Brannan was killed in a car accident.

Phillipa, 16, of White Lion Road, Little Chalfont, died of head injuries after a Ford Mondeo, driven by Graham Lewis, 66 at the time, mounted the footpath and drove into her as she made her way back from a school Christmas fair with her mum and sister on December 7 1996.

Younger sister Tania Hart has spoken out about her pain and grief, and is encouraging those who knew Phillipa to lay flowers or candles under the railway bridge of Chalfont & Latimer Station in Amersham, the site of the crash, on the 20th anniversary of her death.

In a social media post, Mrs Hart, who was 10 at the time, described the events of the day leading up to the heartbreaking moment her sister was hit by the car, saying the walk to Little Chalfont Primary School was “one of the most funniest and joyful moments” she had shared with her.

She wrote: “We were singing and dancing to the song from the R-Whites lemonade advert.

“It was so funny, we all did different voices and dances we were in stitches.”

The family headed home from the fair at around 4.15pm and were walking under the railway bridge when Mrs Hart stopped to tie her shoelaces.

She said: “All of a sudden, out of nowhere, I remember being on the floor.

“I didn't know what had happened – then it descended into chaos.”

She said saw her sister lying in the road and rushed over to see if she was ok, where a group of nurses were looking after her.

The family was taken to hospital, where Mrs Hart said “time seemed to pass so slowly”, and burst into tears when a nurse came into their room to tell them Phillipa’s heart had stopped.

Metal railings were installed on either side of the road, as well as a speed camera, following the accident.

Mrs Hart added: “We found out that people had been complaining to the council about that stretch of road for years but were told one more accident needed to happen before they could do anything.

“Sadly that final accident was our Philly and it makes me very angry when I see those barriers, as if they were there [before] they could have saved her life.”

Phillipa and her dad survived the Bradford Football Club fire, where 56 people died, in 1985. Mr Lewis's wife also died of cancer 11 weeks before the crash.

He was found not guilty of death by dangerous driving, but guilty of careless driving, at Reading Crown Court. He was fined £500 and given four penalty points on his licence.

For more information about the vigil, go to www.facebook.com/events/1714036968917050.