Polly Perks, the thoroughbred mare at the centre of the case A teenager is suing her former boyfriend’s mother for more than £3 million over a horse riding fall that left her paralysed.Ashleigh Harris had recently celebrated her 14th birthday when she broke her back after falling from a thoroughbred mare owned by Rachel Miller.The accident left the keen rider – now 18 – with no function in her legs. She is now suing Mrs Miller at London’s High Court.Miss Harris, of Woolaston, Lydney, in the Forest of Dean, claims the horse, Polly Perks, “misbehaved” in a field in Mathern, near Chepstow when it broke into a canter of her own accord, throwing her off in the process.But Mrs Miller, in her 40s, says the horse was blameless and that Ashleigh fell after losing her balance as she descended a “short and gentle slope”.The court heard Miss Harris had been taken to a field on 22 September 2012 by Mrs Miller, the mother of her then boyfriend, Keiran Miller. Giving evidence, the teenager told the court that she felt Polly was “fidgety” and had been nipping at her and others.Describing her fall, she added: “I had been riding for about five minutes and started trotting Polly.”She then went to canter and I held her up because I didn’t ask her to.”She was throwing her head around and bucked, then I came out of the saddle and went over the horse’s head. I hit the floor and rolled.”David Westcott QC, for Miss Harris, said she should never have been allowed into Polly’s saddle, as she had only ever ridden ponies.Mrs Miller disputes Miss Harris’s version of events, and said the teenager tumbled off Polly as she was riding her at a walking pace down a hill in the field.Judge Wood will give his ruling on the claim at a later date. Miss Harris declined to comment when approached by The Telegraph. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.