Lawyers for the family of three of the Glasgow bin lorry victims have taken the first step to privately prosecute driver Harry Clarke.

It was confirmed on Wednesday that a Bill of Criminal letters was lodged with the lord advocate Frank Mulholland.

Relatives of 18-year-old Erin McQuade and her grandparents Jack and Lorraine Sweeney announced the decision to privately prosecute last month after an inquiry into their deaths found the incident might have been avoided if Clarke had not lied about his history of blackouts.

A statement from the family's lawyer said: "Paul Kavanagh, Gildeas solicitors, intimates on behalf of the relatives of Jack and Lorraine Sweeney and Erin McQuade that a Bill for Criminal Letters was delivered to the lord advocate today.

"We have sought the concurrence of the lord advocate and look forward to receiving a response within seven days.

"This is the initial process that the family hope ultimately will lead to the prosecution of Henry Clarke in the criminal courts."

Mr Clarke, 58, from Baillieston was unconscious when the lorry veered out of control on 22 December 2014, killing them as well as Gillian Ewing, 52, from Edinburgh and Jacqueline Morton, 51, and Stephenie Tait, 29, from Glasgow.

The inquiry found he had "repeatedly lied in order to gain and retain jobs".

Sheriff John Beckett QC noted a number of precautions that might have prevented the tragedy and detailed recommendations in a determination following the fatal accident inquiry at Glasgow Sheriff Court that ended in August after weeks of evidence. Many of the precautions related to Mr Clarke's medical history.

They included: "For Mr Clarke, after fainting at the wheel of his bus on April 7, 2010, to have refrained from continuing to drive buses and to have refrained from seeking further employment as a group two driver in the absence of his having told the truth to doctors and without having acted upon the advice which would have been forthcoming.

"And thereafter without making his relevant medical history known to Glasgow City Council to the extent required in its recruitment, appointment and promotion processes.

"The sheriff suggested that it should be considered that the Crown Office should review policies which prevent or discourage prosecution for offences including giving false statements and withholding information."