- Video report by ITV News Correspondent Juliet Bremner
Speedboat killer Jack Shepherd will remain behind bars after he lost his Court of Appeal challenge against his manslaughter conviction of Charlotte Brown.
The 31-year-old was jailed for six years over the death of Ms Brown, 24, after they both fell into the River Thames when a boat they were on capsized during their first date in December 2015.
Shepherd launched a bid to overturn his conviction for manslaughter by gross negligence at the High Court in London last week.
His lawyers argued the conviction was unsafe as some of the evidence at his trial came from an interview where he was not cautioned or offered a solicitor because of a "mistake" by police.
However Sir Brian Leveson and two other senior judges threw out his appeal on Thursday morning.
Sir Brian said: “When granting leave (to appeal), the single judge made the point that the appellant should not be overoptimistic as to the outcome.
“That warning was prescient. The appeal against conviction is dismissed.”
Speaking outside the High Court in London on Thursday, Charlotte's twin sister Katie said: "We are relieved as a family that Shepherd's appeal against his manslaughter conviction has been thrown out and justice has prevailed.
"My sister Charlie is not here with us today because of Shepherd's negligence and reckless actions.
"He hasn't once shown any remorse or respect to our family, or to the legal system, or to even Charlie."
Charlotte's father Graham Brown praised the decision to quash Shepherd's appeal.
Mr Brown said: "I think the right decision has been made and as a family we are very relieved that the appeal has not been upheld."
He urged the Crown Prosecution Service (CPS) to bring further legal proceedings against Shepherd for skipping bail and going on the run to Georgia.
Mr Brown added: "They have indicated that they are. It does seem bizarre to the layman that (Shepherd) has been able to abscond to Georgia without consequence.
"I think it is very important that that bit is looked at and that people should face consequences for not appearing at their trial."
Shepherd, originally from Exeter, fled the country ahead of his hearing at the Old Bailey and was convicted in absense in July 2018.
He was later extradited to the UK from Georgia after handing himself into police in January this year.
Jurors at Shepherd's trial heard how he and Ms Brown had been drinking champagne and went on a late-night cruise past the Houses of Parliament.
Shepherd handed the controls to Ms Brown before it hit a submerged tree, with both of them then falling into the water.
He was pulled from the water alive, but Ms Brown was found unconscious and unresponsive.
Following his return from Georgia, Shepherd appeared at the Old Bailey in April and was sentenced to an additional six months for breaching bail.
The Court of Appeal quashed his bail conviction and sentence on Thursday, but said he may face further proceedings in relation to his “egregious breach”.
He was jailed for a further four years at Exeter Crown Court earlier this month after he admitted wounding with intent in relation to a drink-fuelled attack on a barman.
The court heard he struck former soldier David Beech with a vodka bottle on March 16 2018 after being asked to leave The White Hart Hotel in Newton Abbot, Devon.