The punishment part of the sentence is 22 years and was backdated from August 18, 2022.
He pled guilty to both charges at a hearing in August 2023.
On June 17, 2024, at the High Court in Glasgow, co-accused Paul Black, 65, was sentenced to five years and six months in jail for attempting to defeat the ends of justice.
Moira Orr, who leads on homicide and major crime for the Crown Office and Procurator Fiscal Service (COPFS), said:
“This was a callous and brutal murder of an elderly man who was quietly enjoying his retirement.
“Peter was loved by his family and friends in the local community. He had a positive impact on the lives of so many people.
“But his own life was cut short by the despicable actions of Paul McNaughton.
“He showed a cavalier disregard for his actions and will now serve a life sentence for his crimes.
“As prosecutors, we have worked hard to deliver justice for Peter and his family. The COPFS team used every tool at our disposal to ensure these two men faced the consequences of their horrific crimes.
“Our thoughts remain with Peter’s friends and family who have waited patiently for justice to be served as they come to terms with today’s outcome.”