The driver of the out-of-control bin lorry which ploughed into pedestrians in Glasgow killing six people was unconscious and slumped over the wheel as the tragedy unfolded, it has been confirmed.

The Sunday Herald can also reveal the 57-year-old had reported "no prior health problems" which could have left him incapacitated as he drove the 14-tonne refuse truck.

A senior council source has moved to quash speculation that the driver did not have a clean bill of health before taking to the wheel on December 22.

Six people died when the bin lorry careered into Christmas shoppers as it travelled along Queen Street and George Square before crashing into the Millennium Hotel.

The source said: "Any health problems happened on the day. They could not have been predicted. To say he had prior health problems is definitely not the case."

The crash claimed the lives of Erin McQuade, 18, her grandparents, Jack and Lorraine Sweeney, who were both in their late sixties, primary school teacher Stephenie Tait, 29, Gillian Ewing, 52, and Jacqueline Morton, 51. Another ten people were injured.

It is understood that the driver, who remains in hospital, and his colleagues who were in the truck, will be offered counselling.

The senior council source said: "A lot of them [the injured] are getting better but nevertheless there were fatalities there and, going forward, it's about how we manage [to cope with] that.

"The driver is going to have to live with it for the rest of his life. It's a tragic situation for all of the guys who were in the truck. "

Last week, the nephew of pensioners Jack and Lorraine Sweeney stressed that the family did not blame the driver.

Marc Gardiner tweeted: "I hope that the driver of the lorry makes a speedy recovery and understands it wasn't his fault."

The senior council source said: "I know the family in Dumbarton were saying they don't blame the driver, he took unwell. I think that will come to fruition."

The source also suggested that there could be an overhaul of ­established processes used by staff in bin lorries.

He commented: "I think what will happen is there is going to be changes to procedures in these big machines."

The Sunday Herald has learned that a major trade union will offer support to the driver while an investigation into the incident is carried out.

A source at the union insisted that the council worker should not be held responsible for the tragic events of December 22.

He said: "Something medical has happened which has left him slumped over the wheel.

"There's nothing that could have been done about it. ­Something happened which left him unconscious."

Police Scotland would not confirm yesterday whether ­officers have spoken to the driver or his colleagues.

A spokeswoman said: "They will obviously need to be spoken to as part of the investigation but we wouldn't say when that happens."

She added: "Inquiries are ongoing and we will be working with all of the agencies involved, including the council."