John Baxter, 58, said that the powerful headlights of his tractor revealed the body, which was partially covered in cut grass.

He had been working in the field at North Glen Farm in Langbank around 1am on 13 July 2004 when he saw the remains of 34-year-old Martin Toner, who had been reported missing by his wife Michelle.

Mr Baxter was giving evidence at the High Court in Glasgow at the trial of Douglas Fleming, 50, and John McDonald, 57, who deny murdering Mr Toner.

The pair are alleged to have killed Mr Toner at the garden and grounds of the Coach House at Gleddoch Estate, Langbank, and Gleddoch Estate on 29 June 2004.

Mr Baxter told advocate depute Alex Prentice QC, prosecuting: “I was picking up the bales and I got to the last bale which was at the gate to the field.

“As the tractor lights came round I saw something lying under the bushes.

“I stopped and reversed back and jumped out of the tractor and went over to within four or five feet from the body.

“I could see the head and a bit of shoulder.

“I had enough sense not to touch anything and telephoned the police.” During Mr Baxter’s evidence the jury were handed a book of photographs and warned that some of them may be distressing.

Mr Prentice told them: “This book contains some graphic images which may come as a shock to those not used to this kind of thing.” The first police officer on the scene 11 years ago was also called to give evidence.

DC Lesley Petrie told the court: “I could clearly see there was a body. As I took a few steps closer I could smell a deceased body.” Fellow witness Dr Angus Blyth, 69, told the court that he was called out to inspect the body in his capacity as a police surgeon.

He said: “He was lying face down at the side of the field.

“On carefully lifting away the grass I noticed an apparent wound under his left jaw.

“There was also what appeared to be bloodstaining on the deceased’s back.

“On gently lifting up his clothing top several stab wounds were noted.

“He had been murdered by stabbing either here or at some other locus and had then been dumped or placed here.” During yesterday’s proceedings, the jury also heard how murder accused Fleming served as a police officer with Central Scotland Police for three years, from January 1985 until November 1988.

The court also heard that at the time of the death of Mr Toner, Fleming was living at the Coach House at Gleddoch Estate with his then partner.

The trial, before Lord Armstrong, continues.