The George Square bin lorry crash driver will not face a private prosecution by victims' families, a court has ruled.

Relatives of three people who lost their lives in the tragedy took their case for Harry Clarke to face a trial to the Appeal Court in Edinburgh earlier this year.

The rare move followed a controversial decision by the Crown Office not to prosecute Mr Clarke over the 2014 tragedy.

Judges Lady Dorrian, Lord Menzies and Lord Drummond Young had been considering the Bill for Criminal Letters since hearing final arguments in the case in October.

The three judges issued their decision on Friday and ruled the families had been unsuccessful in their bid to prosecute Mr Clarke. They found that the Crown had made no error in law previously.

Their written ruling states: "It is quite difficult to conceive of circumstances in which the court would pass a bill where the lord advocate had examined and investigated the circumstances of the case and concluded as a matter of informed judgement that the whole tenor and weight of the evidence did not justify prosecution."

The proceedings were brought by the relatives of those who lost their lives after being struck by a bin lorry being driven by Mr Clarke.

The former Glasgow City Council employee was behind the wheel of the lorry when it struck six people in Glasgow city centre on December 22, 2014.

The judges added that even if they disagreed with the Crown's assessment they would be "unable to conclude that the decision of the Lord Advocate not to prosecute was so extravagantly wrong as to amount to special circumstances justifying the passing of the bills in either case."

Student Erin McQuade, 18, and her grandparents 68-year-old Jack and 69-year-old Lorraine Sweeney lost their lives in the incident.

The other people who died were Stephanie Tait, 29, Jacqueline Morton, 51, and 52-year-old Gillian Ewing.

Crown Office lawyers decided not to prosecute the 59-year-old driver on the basis he had a medical condition that caused him to lose consciousness.

The relatives of Erin McQuade and Jack and Lorraine Sweeney believe prosecutors were mistaken not to bring Clarke to court.

They are being joined by the families of students Mhairi Convy and Laura Stewart, who were knocked down and killed in Glasgow in 2010.

The two women, who were aged 18 and 20, were walking on North Hanover Street when a Range Rover being driven by William Payne mounted the kerb and hit them.

They also failed in their bid to bring a private prosecution against Mr Payne.